perfect blueberry muffins

INGREDIENTS

• 5 tablespoons (2 1/2 ounces or 71 grams) unsalted butter , softened
• 1/2 cup (3 1/2 ounces or 100 grams) sugar
• 1 large egg
• 3/4 cup sour cream or plain yogurt
• 1/2 teaspoon grated lemon zest
• 1 1/2 cups (6 3/4 ounces or 191 grams) all-purpose flour
• 1 1/2 teaspoon (7 grams or 1/4 ounce) baking powder
• 1/4 teaspoon (1 gram) baking soda
• 1/4 teaspoon (2 grams) salt
• 3/4 cup (3 3/4 ounces or 105 grams) blueberries, fresh or frozen (if frozen, don’t bother defrosting)