Stir the flour, salt, and baking powder in a large bowl.
With an electric mixer, cream butter, and sugar.
Add the eggs, vanilla, and milk and mix until well blended.
Gently stir wet ingredients into dry ingredients with a spoon, just until combined.
Spoon about half of the batter into the bottom of 12 greased muffin cups.
Generously sprinkle more than half of the streusel topping onto each muffin. It will look like too much, but be generous with it.
Dollop the remaining batter onto the top of each muffin. It may not be enough to cover the streusel, but the batter will spread out when baking.
Sprinkle the remaining streusel on top of each muffin.
Bake at 400° for 20-25 minutes, until a toothpick comes out clean.