Bring your s'mores indoors with the help of this easy fall dessert. A graham cracker crust and a creamy chocolate and marshmallow topping ensures that all your favorite s'mores flavors are represented in this yummy fall treat.
Preheat oven to 325 degrees F. For crust, in a medium bowl beat the 1/3 cup butter with an electric mixer on medium to high speed for 30 seconds. Add brown sugar and baking soda. Beat until combined, scraping sides of bowl occasionally. Beat in one of the eggs and the vanilla until combined. Beat in the 1/2 cup flour. Using a wooden spoon, stir in the oats and graham cracker crumbs. Reserve 1/2 cup of the crust mixture. Spread remaining crust mixture into the bottom of an ungreased 10-inch tart pan with a removable bottom. Set pan and reserved crust mixture aside.
For filling, in a small heavy saucepan heat and stir 1 cup of the chocolate pieces and 2 tablespoons of the 1/2 cup butter over low heat until just melted and smooth; set aside. In a large bowl beat the remaining butter and the granulated sugar with an electric mixer on medium speed until combined. Add the melted chocolate, the almonds, the 1/3 cup flour, the remaining egg, and the egg yolk; beat until combined. Stir in 1/2 cup of the marshmallows. Spread filling evenly over crust in pan.
Dot the remaining crust mixture over filling. Bake for 45 minutes or until filling is just set. Sprinkle the remaining 1/2 cup marshmallows, and the 1/4 cup milk chocolate pieces over the top. Bake for 5 minutes more. Cool in pan on a wire rack for 10 minutes.
Using a small sharp knife, loosen tart from sides of pan. Remove sides of pan. Cool completely on a wire rack.