Preheat oven to 325 degrees F (165 degrees C). Spray a 9x9-inch pan with cooking spray.
Whisk flour and confectioner's sugar together in a bowl; stir in 1/2 cup butter until crumbly. Press flour mixture evenly into the bottom of prepared pan.
Bake in the preheated oven for 5 minutes. Remove pan from the oven, leaving oven at 325 degrees F (165 degrees C).
Beat brown sugar, eggs, 1/4 cup melted butter, vinegar, and vanilla extract together in a bowl until smooth; stir in raisins. Pour sugar mixture over baked crust.
Bake in the oven until bubbly and golden, about 35 minutes; cool before slicing.