Banana Poppy Seed Cake with Lemon Buttercream

INGREDIENTS

2 tbsp

unsalted butter, at room temperature

2/3 cup

sugar

1/2 cup

sour cream

large egg, room temperature

ripe bananas, mashed (to make about 3/4 cup mashed)

1/3 cup

poppy seeds

1 tsp

vanilla extract

1 cup

flour

1/4 tsp

salt

1/2 tsp

baking soda

lemon buttercream

8 tbsp

(1 stick, 1/2 cup) unsalted butter, at room temperature

2 cups

confectioner's sugar

juice of 1 lemon (about 2 Tbsp)

the tiniest drop of yellow food coloring (optional)