Preheat oven to 350°F (177°C) and grease your muffin tin. (Or, for taller muffins, preheat to 425°F [218°C])
Mix your dry ingredients together in a bowl. Set aside.
In a separate container, mix the liquid ingredients (eggs, milk, melted butter, vanilla) and lemon zest.
Stir the liquid mixture into the dry ingredients, stirring gently until just mixed—the batter should still be somewhat lumpy.
Carefully fold in the blueberries with a silicone spatula.
Portion the batter into the muffin tin.
Now bake. If you are cooking at 350°F the whole time, cook for about 18 minutes. If going for taller muffins, cook at 425°F for 5 minutes, then turn the heat down to 350°F, gently open and close your oven door, and continue cooking for about 10 more minutes.
Check the internal temperature with your Thermapen ONE—it should be 200°F (93°C).
Remove the muffins from the oven. Cool for 5 minutes before removing from the pan. Serve warm with soft butter or cool and store!