Preheat oven to 425 degrees F (220 degrees C).

Cream together softened butter, sugar, lemon oil or zest, and vanilla in a large bowl until light and fluffy.

Add egg yolks or eggs one at a time, beating well after each addition.

In a separate small bowl, whisk together buttermilk (or milk/yogurt), water, and lemon juice.

In a third bowl, sift together flour, baking soda, and salt.

Gradually add the dry ingredients to the butter mixture, alternating with the wet ingredients, beginning and ending with the dry ingredients. Mix until just combined.

Gently fold in frozen blueberries.

Spoon batter evenly into 24 muffin tins, filling each about 3/4 full.

Bake in the preheated oven at 425 degrees F (220 degrees C) for 7 minutes.

Reduce oven heat to 325 degrees F (165 degrees C) and bake for another 10-12 minutes, or until a toothpick inserted into the center comes out clean or the muffins spring back when lightly touched.

Remove muffins from tins immediately and cool on a wire rack.