Not easy, but worth it.

We have new neighbors, not right next to us, but completely diagonal on the same block on the complete other side - so kitty corner, but way on the other side of our actual block. Does that makes sense? We'll go with that for now. Also kitty corner or katty corner? I never know. Let's get even more real, they aren't even that new. They have lived there a year and for a year they walk their dog past and we talk and chat and they are wonderful people! Those wonderful people decided we needed to have a neighborhood BBQ - Yes!! Dang it! We had another party that night too! We decided to double book it! We walked over to chat with them and meet a few people then headed to a birthday party we had to get to too. I made these Mud Pie Bars thinking somehow it wouldn't be too hard to make. Look at all these layers and steps? Are they worth it? Yes! For sure! But oof! On an already busy day, it sure made things interesting. We had a lovely 45 minutes at the neighbors meeting other neighbors and trying to figure out who belonged to what house, then off to the next place. Hopefully next time we won't have to race off and we'll get a chance to hang out more. Hopefully they enjoyed the bars, we had a few left over at home and they sure tasted great to us!

Mud Pie Bars
Crust
200g chocolate wafer cookies or oreos with the filling taken out
70g unsalted butter, melted and cooled

Cake
225g semisweet or bittersweet chocolate
170g unsalted butter
2 Tbsp Dutch process cocoa powder
250g granulated sugar
5 large eggs, at room temperature
1 tsp vanilla extract
¼ tsp salt
36g all-purpose flour

Chocolate Mousse
600g heavy cream
5 large egg yolks, at room temperature
50g granulated sugar
¼ tsp salt
1 tsp vanilla extract or paste
225g semisweet or bittersweet chocolate, finely chopped

Whipped Cream
360g heavy cream
2 Tbsp granulated sugar
1 tsp vanilla bean paste or extract
pinch of salt

CHOCOLATE CRUST
Adjust an oven rack to the middle of the oven. Preheat the oven to 350°f / 180°c.
Grease a 9" x 13" (23 x 33cm) pan and line it with a parchment sling.
Place cookies in the bowl of a food processor and process until broken down into fine crumbs. Move the crumbs to a medium bowl, and pour the melted butter over the top. Use a spatula to stir together until combined.
Press the mixture onto the bottom of the prepared pan and bake for 10 minutes. Remove the pan from the oven and let cool.
CHOCOLATE CAKE
Keep the oven temperature at 350°f / 180°c.
In a small saucepan, melt the chocolate and butter together over low heat, stirring frequently, until smooth. Remove from the heat and stir in the cocoa powder.
In a large bowl, whisk together the sugar, eggs, vanilla, and salt until smooth. Add the flour and mix again until combined. Add the warm chocolate and whisk into the batter until combined. Let the mixture sit for 15 minutes.
Pour the cake batter over the cooled, baked crust and use an offset spatula to smooth the top.
Bake the cake until the edges are set and the center jiggles slightly, 15 to 18 minutes. Remove from the oven and let cool completely on a wire rack. Cover the pan with plastic wrap and refrigerate for 4 hours, or overnight.
CHOCOLATE MOUSSE
Heat 240g of the heavy cream in a small, heavy saucepan until hot.
In a medium saucepan off the heat, whisk the egg yolks. Whisking constantly, slowly add the sugar to the egg yolks, then the salt, and then slowly pour in the warmed heavy cream. Cook over medium heat, stirring constantly, until the mixture registers 160°f. Pour the mixture through a fine-mesh sieve into a large bowl and stir in the vanilla.
In a small saucepan over low heat, melt the chocolate, stirring frequently until smooth. Whisk the chocolate into the custard until smooth, then let cool.
In the bowl of a stand mixer fitted with the whisk attachment (or just using a mixing bowl and whisk), beat the remaining 360g heavy cream until stiff peaks form. Whisk one-third of the whipped cream into the chocolate custard to lighten it, then gently fold in the remaining whipped cream.
Transfer the mousse to a large bowl and cover the bowl with plastic wrap. Refrigerate for 4 hours, or overnight.
WHIPPED CREAM
Ten minutes before whipping the cream, place the bowl and whisk from a stand mixer (or a hand whisk) in the freezer and let chill. In the chilled bowl, whisk together the heavy cream, sugar, vanilla, and salt for 30 to 45 seconds. Increase the speed to medium and beat for 30 to 45 seconds. Increase the speed to high and beat until the cream is smooth, thick, and nearly doubled in volume, 30 to 60 seconds. The whipped cream can be made 2 hours ahead and stored in the fridge.
ASSEMBLY
Transfer the chilled chocolate mousse onto the top of the baked, cooled cake. Use an offset spatula to even the top. return the bars to the fridge and let chill for 1 hour.
When ready to serve, cover the bars with the whipped cream. Coat the top with grated chocolate, if desired. Use the parchment sling to remove the cake from the pan, and cut into slices. Bars can be stored in the fridge in an airtight container for up to 5 days.