Streusel
1. Place all ingredients in a food processor and grind together to make a rough powder.

Cake
1. Preheat a conventional oven to 350°F.
2. Place Plugrá Butter, sugar and vanilla bean in a mixer and cream until soft and fluffy. Add the egg and egg yolk one at a time until they are well incorporated into the creamed mixture.
3. Combine all of the dry ingredients in a mixing bowl.
4. Add ½ of the dry ingredients and ½ of the crème fraiche to the creamed mixture and continue mixing until all the ingredients are combined well. Add the remaining dry ingredients and remaining crème fraiche and mix until all the ingredients are combined.
5. Line an 8x8 inch metal pan with parchment paper. Layer half of the cake batter into the lined pan. Spread the blueberries on top of the cake batter in a neat layer. Sprinkle half of the pecan streusel over the blueberries. Next, carefully spread the remaining half of the cake batter and top with the remaining streusel.
6. Bake for approximately 35 minutes or until the cake springs back to touch in the center of the cake.

Warm Blueberries
1. Place all ingredients in a saucepan over medium heat.
2. Cook until the berries start to give off a little juice and are glossy.