Preheat your oven to 350°F (175°C). This ensures your muffins bake evenly and rise beautifully.
Grease your muffin tin with a bit of butter or line it with muffin liners for easy removal.
In a large mixing bowl, beat the butter and granulated sugar together until light and fluffy, about 3-4 minutes. This step is crucial as it incorporates air into the mixture.
Mix in the lemon zest, Greek yogurt, vanilla extract, and eggs. Beat well until all ingredients are fully combined.
In a separate bowl, whisk together the white whole wheat flour, baking powder, and salt. Gradually add this mixture to the wet ingredients, stirring gently until just combined. Be careful not to overmix!
Gently fold in the blueberries and blueberry jam until evenly distributed throughout the batter.
Spoon the batter into the prepared muffin tin, filling each cup about 3/4 full.
In a small bowl, mix together the granulated sugar, cinnamon, and melted butter. Sprinkle this mixture generously over the muffin batter.
Place the muffin tin in the preheated oven and bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean.
Let the muffins cool in the pan for about 5 minutes before transferring them to a wire rack to cool completely. Enjoy your Blueberry Yogurt Coffee Cake Muffins warm or at room temperature!