For the streusel topping:

In a small bowl add all ingredients and stir well to combine. Set aside.

For the muffins:

Preheat oven to 350 degrees and line a 12-count muffin pan with paper liners, set aside.

In a medium sized bowl add flour, baking powder, fresh thyme leaves and kosher salt. Whisk to combine and set aside.

In a small bowl (or use your liquid measuring cup) add buttermilk, lemon zest, vanilla bean paste and lemon extract. Stir to combine and set aside.

In the bowl of an electric mixer add butter. Cream until light in color and smooth. Add in brown sugar and mix again until the mixture is fluffy, lighter in color and well combined. Mix in eggs, 1 at at time, until well combined.

While the mixer is one low speed slowly add in the flour just until combined.

Gently stir in the fresh blueberries trying not to break them as you stir.

Fill your muffin pans about 3/4 of the way full and smooth the top as best as possible.

Top each muffin with a handful of streusel topping. If the topping sets up a bit (the butter might firm up a bit) just break it up with your hands. You want to use all the topping so don’t be scared to really top those muffins.

Bake for about 25 minutes or until the muffin is fully cooked. You can test your muffin by inserting a toothpick into the center and when removed it should be clean.

Let your muffins cool and top with drizzle.

For the glaze: 

Whisk together until smooth. If it’s too thick add a little more lemon juice. If it’s too thin add a little more powdered sugar.