Bisquick Apple Custard Coffee Cake

2 1/2 cups Bisquick baking mix
3 tablespoons sugar
3 tablespoons butter, melted
1/2 cup milk
1 1/2 cups sliced pared apples
1/4 cup sugar
1/2 teaspoon ground cinnamon
2/3 cup sour cream
1 egg

Mix baking mix, 3 tablespoons sugar, butter and milk. Spread in greased 9 x 9 x 2 inch square pan. Mix 1/4 cup sugar and the cinnamon; sprinkle over apple. Mix sour cream and egg; drizzle over top. Bake at 375 degrees for 25-30 minutes until edges are light brown. Refrigerate any remaining coffee cake. 9 servings.

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