Preheat oven to 350°F (175°C). Grease a 9×13-inch pan and prepare the yellow cake mix with eggs, water, and oil according to package directions. Pour batter into pan and bake for 22–25 minutes, or until a toothpick comes out clean.

Let the cake rest for 10 minutes on a wire rack so it’s warm but not hot—too-hot cake can absorb the filling unevenly.

Use the handle of a wooden spoon to poke holes evenly across the entire surface, pressing down about 1 inch deep to create perfect pockets for the cannoli cream.

In a bowl, whisk together ricotta, mascarpone, 3/4 cup powdered sugar, and 1/2 teaspoon vanilla until smooth and creamy.

Gently spoon or pipe the cannoli filling over the cake, pressing some filling into each hole and spreading the rest evenly on top.

In a chilled bowl, beat heavy cream, remaining 2 tablespoons powdered sugar, and 1/2 teaspoon vanilla until stiff peaks form, then dollop or spread over the filled cake.

Sprinkle mini chocolate chips and optional chopped pistachios evenly over the whipped cream layer for that classic cannoli crunch.

Refrigerate the cake for at least 2 hours (or overnight) so flavors meld and the filling sets. Slice into 12 pieces and enjoy.