Preheat the oven to 375°F and lightly grease the cups in a mini (or standard - see notes) muffin tin.
Place the chopped pineapple in a fine-mesh strainer, set it over a bowl and, using the back of a large spoon, press out the excess juice. Let the pineapple continue draining while you prepare the muffin batter.
Whisk the flour, baking powder, baking soda and salt together in a mixing bowl and set aside.
In a larger mixing bowl, whisk the egg, milk and sugar together until frothy, then stir in the melted butter, lemon extract and lemon zest.
Add the dry ingredients and mix until thoroughly blended, then stir in the pineapple. The batter will be rather thick.
Divide the batter between the prepared muffin tins and bake for 11 to 13 minutes or until a toothpick inserted into the center of a muffin at the center of the pan comes out clean.
Cool the muffins in the pan for 5 minutes, then transfer to a cooling rack. Store in an airtight container and refrigerate after one day.
Tips for Making This Recipe
To make standard-sized muffins:
Follow the recipe as written and increase the baking time to 14 to 16 minutes.