Almond-Lemon Bars

Ingredients

• Cooking spray
• 1.3 ounces potato starch (about 1/4 cup)
• 1.15 ounces brown rice flour (about 1/4 cup)
• 0.9 ounce almond meal flour (about 1/4 cup)
• 1/4 cup packed brown sugar
• 1 tablespoon butter, softened
• 1/2 teaspoon salt, divided
• 1/4 teaspoon almond extract
• 1 1/2 cups granulated sugar
• 2 tablespoons white rice flour
• 2 tablespoons grated lemon rind
• 6 tablespoons fresh lemon juice
• 1 teaspoon baking powder
• 4 large eggs
• 2 teaspoons powdered sugar