Cream together sugar, sour cream, egg, and 2 tablespoons softened butter.
Add mashed bananas and 1 teaspoon vanilla extract. Mix again.
Add flour, salt, and baking soda; mix well.
Pour into greased 8x8 pan.
*Bake at 375F for 20-25 minutes until a toothpick inserted in the center comes out clean. Cool completely before frosting. (See note)
Frosting
Cream butter and confectioner's sugar together until smooth.
Slowly add the heavy cream; stir until smooth.
Stir in the vanilla bean paste until fully incorporated. Spread on cooled cake.
Notes
*Bake at 350F if using a glass pan. Recipe doubles well to fit in a 9x13 pan. **Here's the general rule for substituting vanilla: 1 vanilla bean = 1 tablespoon vanilla powder = 1 tablespoon vanilla bean paste = 1 tablespoon pure vanilla extract
Recipe by Mandy's Recipe Box at https://mandysrecipeboxblog.com/banana-cake-with-vanilla-bean-frosting/