This cake is perfect for beginners—it's moist, forgiving, and easy. Creamy peanut butter is the best for the decadent frosting. I should mention that this is cake is also excellent with a fudgey chocolate frosting.
Preheat oven to 350°F Coat cake pans with nonstick spray. Line bottom of pans with parchment; coat paper. Whisk flour, baking soda, and salt in a medium bowl. Using an electric mixer, beat sugar, butter, and brown sugar in a large bowl until light and fluffy, about 3 minutes. Add eggs one at a time, beating to blend between additions and occasionally scraping down sides and bottom of bowl. Beat in vanilla.
Add dry ingredients; beat on low speed just to blend. Add bananas and sour cream; beat just to blend. Fold in mini chips. Divide batter evenly among pans; smooth tops.
Bake cakes until a tester inserted into the center comes out clean, about 35 minutes. Transfer to wire racks; let cool in pans for 10 minutes. Invert cakes onto racks; peel off parchment and let cool completely.
Using an electric mixer, beat first 4 ingredients in a medium bowl until a light and fluffy frosting forms, 2–3 minutes.
Place 1 cake on a platter. Spread 1 1/4 cups frosting over. Place remaining cake on top. Cover top and sides of cake with remaining frosting. Garnish with chocolate chips and kisses.
Cake can be made 2 days ahead. Cover and chill. Let stand at room temperature for 1 hour before serving.