Preheat your oven to 375 degrees.
Cream together your butter and sugar in a large mixing bowl.
Slowly mix in the eggs, one at a time, until just mixed after each.
Stir in the vanilla extract.
Combine the flour, baking powder and salt in a separate bowl.
Add half of the flour mix, then mix until just combined. Then half of the buttermilk, mix until combined. Remaining flour, stir until combined. The final buttermilk, stir until combined.
Carefully fold the raspberries into the batter.
Divide the batter into 18 muffin liners (1.5 pans worth). Filling them each about 3/4 full.
Sprinkle crumb evenly over the top of all muffins, if desired.
Bake in the preheated oven for about 20 minutes, or until a toothpick comes out clean.
Let muffins cool 5-10 minutes in the pan before removing them to a cooling rack to cool completely.