Grandma's Banana Cookies

Step 1
Preheat the oven to 350 degrees F (175 degrees C). Grease a cookie sheet.

Step 2
Combine flour, baking powder, and salt in a large bowl. Stir baking soda into sour cream in a separate large bowl; add mashed banana and vanilla.

Step 3
Cream margarine and sugar in a large bowl with an electric mixer. Beat in eggs. Mix in banana-sour cream mixture until incorporated. Add dry ingredients until well combined. Stir in nuts.

Step 4
Drop small spoonfuls of batter onto the prepared cookie sheet; cookies do not expand much in the oven.

Step 5
Bake in the preheated oven, checking occasionally, until bottoms are light golden brown and cookies are set but still a tad soft, 10 to 12 minutes. Remove cookies to a rack to cool.

Step 6
While the cookies are cooling, prepare frosting: Melt butter in a saucepan over medium-low heat. Stir in brown sugar and reduce heat to low. Stir and bring to a boil. Boil, stirring constantly, for 2 minutes. Remove from heat.

Step 7
Stir in 1/4 cup milk and bring to a boil again. Remove from heat and let cool, 10 to 15 minutes.

Step 8
Gradually stir in powdered sugar until frosting is desired consistency. If frosting hardens while working, stir in a little bit of milk.

Step 9
Spread frosting on cooled cookies.