Preheat the oven to 350 degrees F (175 degrees C). Line a 9x13-inch pan with heavy aluminum foil.

Mix flour, 1 cup butter, and white sugar together until mixture is crumbly. Press into the bottom of the prepared pan.

Bake in the preheated oven for 20 minutes.

Blend brown sugar, eggs, salt, baking powder, and vanilla extract together in a bowl. Drain and chop cherries, reserving the liquid. Stir cherries and walnuts into the egg mixture. Place mixture on top of the baked crust.

Return to the oven and bake until set, about 25 minutes. Remove from the oven and let cool.

Combine powdered sugar and 1 1/2 tablespoons butter with enough cherry liquid to spread easily. Frost cooled bars. Cut into squares after icing has set.