2-3ripe bananasmashed (to make about 3/4 cup mashed)
8Tbsp1 stick, 1/2 cup unsalted butter, at room temperature
juice of 1 lemonabout 2 Tbsp
the tiniest drop of yellow food coloringoptional
Set oven to 350F Lightly spray a 9x9 square baking pan. I like to line it with parchment paper so I can lift the cake out after baking for easy frosting and cutting.
Cream the butter, sugar, and sour cream together until light and fluffy. Beat in the egg, mashed banana, poppy seeds, and vanilla.
Whisk the flour, salt, and baking soda together and add to the wet ingredients. Mix until just blended.
Turn the batter out into the pan and smooth out evenly. Bake for about 35 minutes, or until the top is just turning golden and the middle is set. A toothpick inserted in the center should be free of wet batter.
Let cool on a rack completely before frosting.
Make the frosting by beating the butter and sugar together with the lemon juice and food coloring, if using. Add a touch more juice if the frosting is too thick, or a little more sugar if too thin.
I like to store the cake in the refrigerator, and it will keep for up to a week.
Add the zest of the lemon to the frosting if you like for even more lemony flavor.
Substitute chopped walnuts or pecans for the poppy seeds.
Substitute cream cheese for the butter in the frosting.