Really Good Coffee Cake

 3/4 c. sugar

1/2 c. milk

1/4 c. melted butter

1/4 c. sour cream

2 tsp. vanilla

1 egg

1 1/2 c. flour

1 tsp. cinnamon

1/2 tsp. baking powder

1 tsp. salt.

Topping

3/4 c. brown sugar

1/4 c. flour

2 tsp. cinnamon

3 T. melted butter