sweet potato casserole with praline topping

I was never a big fan of sweet potato casserole until this recipe. this the only way I will eat sweet potatoes.

1 cup all-purpose flour
2/3 cup packed brown sugar
1/4 cup chopped pecans
1/4 cup coconut
1/4 cup stick margarine, melted
1/2 teaspoon ground cinnamon
2 cans sweet potatoes or yams, drained
1/2 cup granulated sugar
1-1/2 teaspoons vanilla extract
1 large egg white
1 (5-ounce) can fat-free evaporated milk
Cooking spray

1. preheat oven to 350°
2. combine flour, brown sugar, pecans, coconut, margarine, and cinnamon in a small bowl, stirring to form a streusel and set aside
3. mash potatoes in a large bowl and stir in 1 cup streusel, granulated sugar, vanilla, egg white, and milk
4. spoon into a 2-quart casserole coated with cooking spray; top with remaining streusel
5. bake at 350° for 45 minutes