In a small bowl, add white sugar, flour, and butter. Mix together with a fork or fingertips. The streusel is ready when the mixture looks like coarse sand and there are bigger and smaller pieces of butter. Set aside in the fridge while you make the donuts.
5 tbsp butter, 1/3 cup white sugar, 3/4 cup all-purpose flour
Preheat the oven 350°F/180°C and grease a 6 donut pan with oil. Set aside.
In a large bowl, whisk together vanilla, sour cream, egg, and butter.
2 tbsp butter, 1/2 cup sour cream, 1 tbsp vanilla, 1 egg
Add in the brown sugar and whisk.
1/3 cup light brown sugar
Add the flour, baking powder, and salt and fold in gently using a spatula until no dry streaks appear. Do not over-mix!
1 cup all-purpose flour, 1 tsp baking powder, 1/2 tsp salt
Place batter in a large plastic bag and cut off about ½" from the tip. Divide donut batter evenly between all 6 donuts.
Gently press fresh 4-5 fresh raspberries evenly into each donut. Then top off by sprinkling with streusel.
24 fresh raspberries
Bake for 18-20 minutes. You'll know it's ready when you push on the donuts and they spring back in the pan.
Cool for 2-3 minutes before gently running a knife around the donuts, popping them out of the pan, and placing on a cooling rack. Once slightly cooled, dust with icing sugar (optional).
Enjoy! I like to eat these donuts warm. They are best served day of!