Preheat the oven to 375 degrees F (190 degrees C.) Grease the bottom of a 9-inch square pan.

Beat 1/2 cup sugar and 1/4 cup butter in a large bowl with an electric mixer until creamy.

Combine flour, baking powder, and salt in a small bowl: stir mixture into butter mixture. Stir in milk until thick and slightly lumpy. Spread batter into the prepared pan.

Combine remaining 3/4 cup sugar, berries, and boiling water in a large bowl; pour over batter in the pan. Dot with butter over top.

Bake in the preheated oven for 45 to 50 minutes.