Mississippi Mud Pie Recipe

Mississippi mud pie is a rich chocolate dessert built in four layers: a crunchy chocolate cookie crust, a soft baked fudge layer, a cold chocolate mousse, and a thick cap of whipped cream. This version fills a 9 inch pie dish, cuts into 12 slices, and takes about 4 hours from start to finish, most of it waiting while the mousse sets in the fridge.

The part that decides how it turns out is the fudge layer. Take it out of the oven while the middle still jiggles, and it stays dense and silky instead of baking into a brownie.

• Pan: one 9 inch pie dish, crust pressed up the sides
• Oven: 350°F for the crust (8 to 10 minutes), 325°F for the fudge (15 to 18 minutes)
• Chill: at least 3 hours once the mousse is on
• Total time: 3 hours 55 minutes: 30 minutes prep, 25 minutes baking, 3 hours chilling
• Serves: 12 slices

What Is Mississippi Mud Pie?

It is a Southern chocolate pie named for the dark, thick mud along the banks of the Mississippi River. Recipes differ from kitchen to kitchen, but most stack the same things: a chocolate crumb crust, something fudgy, something creamy, and whipped cream on top. In this one that means crushed chocolate sandwich cookies, a custardy fudge made with chocolate chips, cream and eggs, and a mousse of melted chocolate folded into whipped cream.

It turns up in crosswords often enough that people search the clue. If you came here from “Mississippi ___ (rich chocolate dessert),” the answer is MUD PIE.

Mud Pie or Mud Cake: Which One Are You Making?

The names get mixed up all the time, and they are different desserts.

• Mississippi mud pie: a crumb crust in a pie dish with chilled layers of fudge and mousse, served cold in slices. That is this recipe.
• Mississippi mud cake: a chocolate sheet cake baked in a 9×13 pan, covered with marshmallows while hot, then poured over with chocolate frosting, often with pecans. It is served at room temperature in squares.

For a sliceable chocolate dessert with a softer, cakier bite, try chocolate mousse cake; for a simpler one-filling pie, there is this chocolate pie.

Pressing an Oreo Crust That Holds Its Shape

You need 24 chocolate sandwich cookies, such as Oreos, and 6 tablespoons of melted unsalted butter. Crush the cookies filling and all in a food processor. The cream filling helps bind the crumbs, so do not scrape it out. Pour in the butter and pulse until the crumbs look like wet sand and hold together when you squeeze a handful.

Press the crumbs over the bottom and up the sides of a 9 inch pie dish. Use the flat bottom of a glass or a measuring cup and lean on it; loose crumbs are why a crust falls apart under the knife. Bake at 350°F for 8 to 10 minutes. The crust will still feel a little soft when hot and firms as it cools. Let it cool completely, and lower the oven to 325°F for the fudge.

Baking the Fudge Layer to a Soft Wobble

Melt 1 cup semi-sweet chocolate chips with ½ cup heavy cream, in a bowl over simmering water or in the microwave in 20 second bursts, stirring until smooth. In another bowl whisk ½ cup sugar with 2 large eggs.

Now pour the warm chocolate into the eggs in a thin stream while you whisk. Going slowly warms the eggs gently; dump it in all at once and you can get tiny cooked bits of egg. Stir in 2 teaspoons vanilla and pour it into the cooled crust.

Bake at 325°F for 15 to 18 minutes. Give the dish a gentle nudge: the outer ring should be set and the middle 2 to 3 inches should jiggle like set gelatin, not ripple like liquid. It keeps firming as it cools. If the whole surface looks firm and starts to crack, it has gone too far and will eat like a brownie, still good, just not silky. Cool it completely, until the bottom of the dish feels cool to your hand.

Folding the Chocolate Mousse Without Deflating It

The mousse uses 1 cup chocolate chips and 1½ cups heavy cream, split. Melt the chips with ½ cup of the cream until smooth, then let it cool. Whip the remaining 1 cup cream with 2 tablespoons powdered sugar to stiff peaks.

Temperature matters most here. Touch the chocolate: it should feel barely warm. Too warm and it melts the whipped cream into a runny layer. Too cold and it firms into little chocolate flecks when the cream hits it. Stir about a third of the whipped cream into the chocolate to loosen it, then fold in the rest with a spatula, scraping from the bottom, just until no white streaks remain.

Spread the mousse over the cooled fudge and chill for at least 3 hours, until it is firm when you touch the center. The same folded mousse is the base of a chocolate mousse filling for cakes, if you end up with a taste for it.

Whipped Cream Rosettes and Chocolate Curls on Top

Whip 1½ cups heavy cream with 3 tablespoons powdered sugar and 1 teaspoon vanilla to stiff peaks. Cold cream in a cold bowl whips faster and holds better. Stop as soon as the peaks stand up; keep going and it turns grainy, then buttery. Spoon it on in swoops or pipe rosettes with a star tip. For a cream that holds longer at room temperature, a stabilized whipped cream frosting works on top too.

For curls, run a vegetable peeler along the side of a chocolate bar. A bar that is slightly warm, held in your hands for a minute, curls instead of splintering. Finish with shavings or chocolate sticks and a light dusting of cocoa powder.

Runny Mousse, Crumbly Crust and Other Mud Pie Fixes

• Mousse never set: the chocolate was too warm when the cream went in, or the fudge underneath was still warm. Give it a few more hours in the fridge; a short spell in the freezer helps too.
• Grainy flecks in the mousse: the chocolate had cooled too far. It tastes the same; next time fold while it still feels barely warm.
• Crust crumbles when sliced: the crumbs were pressed too lightly or not baked. Press hard with a glass and bake the full 8 to 10 minutes.
• Fudge layer is dry: it baked until fully firm. Pull it while the center still jiggles.
• Fudge is still liquid after cooling: it came out too soon. Next time bake toward 18 minutes and check the wobble again.
• Layers slide apart: each layer went on before the one below was cool or set.

Making Mississippi Mud Pie a Day Ahead

This pie is better made ahead. Bake the crust and fudge, add the mousse, cover, and refrigerate up to 1 day. Whip and pipe the whipped cream and add the chocolate decorations just before serving, so the cream stays tall and fresh.

For clean slices, dip a sharp knife in hot water, dry it, cut, and wipe the blade before every slice. Serve it cold, straight from the fridge. Cover leftovers and keep them refrigerated for up to 3 days; the whipped cream softens a little by the second day.

If chocolate pies are your thing, French silk pie has a whipped chocolate filling, Oreo pie uses the same cookie crust, and chocolate cream pie trades the mousse for a stovetop pudding. For the fudge layer without the pie, there are fudgy brownies.