Blueberry Lemon Curd Muffins (100% whole grain, dairy-free options)

First, prepare the streusel. Mix all the ingredients together until it resembles coarse crumbs. You can use a pastry cutter but I prefer to use my fingers.
Preheat the oven to 400°F (205°C) and line 2 muffin pans with 16 muffin liners.
In a large bowl, mix together all the dry ingredients, including the blueberries.
2 1/4 cups (281 grams) white whole wheat, 3/4 cup (176 grams) unrefined sugar, 3/4 teaspoon salt, 1 teaspoon baking powder, 1/2 teaspoon baking soda, 1 tablespoon lemon zest, 1 1/4 cup (185 grams) blueberries
In a medium bowl, mix together the lemon extract, oil, and buttermilk.
1 teaspoon lemon extract, 1/3 cup canola oil, 1 1/2 cups (354 ml) buttermilk
Add the wet mix to the dry mix and stir just until combined.
1/2 cup (100 grams) unrefined sugar, 1/2 cup (50 grams) rolled oats, 1/3 cup + 1 tablespoon (50 grams) white whole wheat, 4 tablespoons (56 grams) cold unsalted butter
Fill the muffin liners halfway, dollop 1 tablespoon of lemon curd on top, and then fill with more batter, almost all the way to the top.
1 cup (226 grams) lemon curd
Sprinkle the streusel over the tops of the muffins.
Bake the muffins for 18 - 20 minutes or until a toothpick comes out clean. Make sure not to insert the toothpick in the very center where the curd is! It'll come out wet, if you do.
Let the muffins cool for 5 minutes in the pan and then remove to a wire rack to cool completely.
Cover and refrigerate in an airtight container for up to 5 days.