Preheat oven to 425F. Line a 12-cup muffin tin.
In a large bowl, combine the flour, sugar, baking powder, baking soda, and salt. Mix well.
Create a well in the center of the flour mixture, then add the olive oil, sourdough discard, yogurt, egg, and vanilla extract. Mix with a whisk just until combined. If your yogurt is on the thicker side, add a few tablespoons of buttermilk to loosen up the batter slightly - but not too much, this is a thicker batter!
Add the frozen wild blueberries and chopped chocolate. Fold all together with a spatula.
Divide the batter between the muffin liners.
To make the streusel, combine all ingredients in a bowl and mix until crumb-like texture. Evenly distribute between the muffins.
Bake for 8 minutes, then reduce oven heat to 350F (without opening the doors) to bake an additional 10-12 minutes, until slightly golden on top. To test if done, stick a toothpick in the center and see if it comes out clean.
Let cool at least 10 minutes before enjoying!