1 1/2 cups all-purpose flour
1/2 teaspoon baking powder
1/2 teaspoon salt
12 tablespoons butter (room temperature)
1 3/4 cups packed brown sugar
1 tablespoon vanilla extract
3 eggs
1 1/4 cups toffee bits
1 cup finely diced banana (1/4-inch cubes)
Confectioners' sugar

Line a 9-inch square cake pan with parchment or wax paper. Grease and flour paper and sides of pan.

Whisk flour, baking powder and salt in a bowl.

In another bowl, beat butter and sugar with a mixer until fluffy. Add vanilla extract. Beat in eggs briefly, one at a time, until blended.

Add flour mixture a little at a time, beating on low speed just until blended. By hand, stir in 1 cup toffee bits and banana.

Pour into prepared pan. (If using an 8-inch-square pan, bake the excess batter in greased and floured mini muffin tins.) Sprinkle remaining 1/4 cup toffee bits on top.

Bake at 350 degrees F for 30 minutes (20 minutes for mini muffins). Cool, then remove from pan and cut into 9 to 16 squares.