Preheat oven to 350 degrees.
Place sweet potatoes in a pot and cover with water, bring water to a boil, then simmer for approximately 20 minutes, or until tender.
Drain sweet potatoes, then place in a large bowl and mash them.
Combine flour, brown sugar, pecans, butter and cinnamon in a small bowl.
Mix 1 cup of praline flour mixture into mashed sweet potatoes.
Next, stir in sugar, vanilla, egg & evaporated milk.
Place sweet potato mixture in an 8x8 baking dish coated with cooking spray or butter.
Top with the remaining praline flour mixture and bake at 350 Degrees for approximately 45 minutes, or until topping begins to lightly brown.
Remove from oven and cool on wire rack for 10 minutes before serving.