Preheat oven to 375°F (or 450°F for mini muffins).

Prepare desired flavorings (mocha chips, apricots, raspberries, cranberries, walnuts, orange zest, lemon zest, blueberries, bananas, poppy seeds).

Whisk together flour, baking powder, baking soda, and salt in a medium bowl.

In a separate bowl, cream softened butter and sugar with an electric mixer until light and fluffy (about 2 minutes).

Beat in eggs, one at a time, until well combined.

Gradually add the dry ingredients and yogurt in alternating portions (1/3 at a time), mixing until a smooth, thick batter forms.

Grease a 12-cup muffin tin with cooking spray or butter.

Divide the batter evenly among the muffin cups using a large ice cream scoop.

Bake for 25 minutes for large muffins (or 12 minutes for mini muffins), until golden brown.

Let the muffins cool in the tin for 5 minutes before transferring to a wire rack to cool slightly.

Serve warm.

For mocha chip muffins: Dissolve espresso powder in yogurt and fold chocolate chips into the batter.

For apricot almond muffins: Cream almond paste with butter and sugar and fold diced dried apricots into the batter. Sprinkle with sliced almonds before baking.

For raspberry almond muffins: Cream almond paste with butter and sugar. Spoon half the batter into muffin cups, create a well, fill with raspberry jam, and top with remaining batter.

For cranberry-walnut-orange muffins: Add orange zest to the butter-sugar mixture and fold cranberries and walnuts into the batter.

For lemon blueberry muffins: Add lemon zest to the butter-sugar mixture and fold flour-tossed blueberries into the batter.

For banana walnut muffins: Add nutmeg to the dry ingredients, substitute brown sugar for granulated sugar, and fold diced bananas and walnuts into the batter.

For lemon poppy seed muffins: Add poppy seeds to the dry ingredients and lemon zest to the butter-sugar mixture. Brush warm muffins with lemon syrup.