In a standing mixer with a whisk attachment, whip the cream and sugar until medium to stiff peaks form.
For layer one, spread a small dollop onto a large cake stand, then place one donut in the center. Place five doughnuts around it, creating your first layer. Spoon about 3/4 cup whipped cream over the doughnuts, then repeat the process for your second layer- one doughnut in the center, five doughnuts around it, and 3/4 cup whipped cream on top.
For layers three and four, place four doughnuts onto the cake, creating a pyramid of sorts. Again, add 3/4 cup whipped cream in between the layers.
For layer 5, place 3 doughnuts in a triangle, then add 1/4 cup whipped cream, just in the center.
For layer 6, place a single doughnut on top!
To make the fudge sauce, heat the heavy cream in a small saucepan until scalding. Remove from heat and add in chocolate chips. Stir until combined. Allow sauce to cool slightly before drizzling over the cake!