Preheat your oven to 350°F (175°C). This ensures that your muffins bake evenly.
Grease your muffin tin with cooking spray or line it with muffin liners to prevent sticking and for easy cleanup.
In a large mixing bowl, beat the room temperature salted butter and 1/2 cup of granulated sugar together until light and fluffy, about 2-3 minutes with an electric mixer.
Add the lemon zest, Greek yogurt, vanilla extract, and room temperature eggs to the butter and sugar mixture. Beat until well combined.
In a separate bowl, whisk together the white whole wheat flour, baking powder, and salt to evenly distribute the leavening agents.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Avoid overmixing; a few lumps are fine.
Gently fold in the blueberries and blueberry jam using a spatula to evenly distribute without breaking the berries.
Spoon the muffin batter evenly into each muffin cup, filling them about 2/3 full.
In a small bowl, combine 1/2 cup granulated sugar, 2 teaspoons cinnamon, and melted butter. Mix until crumbly to create the topping.
Sprinkle the cinnamon-sugar topping generously over each muffin. Bake in the preheated oven for 18-20 minutes, or until a toothpick inserted comes out clean.
Remove muffins from oven and let cool in the tin for 5 minutes before transferring to a cooling rack. Enjoy warm or at room temperature.