Preheat oven to 375°F. Butter a 12-cup muffin pan thoroughly, making sure to coat the sides, bottoms, and edges of each cup.

In a medium saucepan over medium-low heat, melt the butter. Stir in the milk and increase the heat to medium. Bring to a light boil, then add the flour all at once. Stir vigorously until the dough forms a smooth ball and pulls away from the sides of the pan. Cook for 1-2 minutes while stirring. Remove from heat and transfer dough to a mixing bowl. Let cool for 5 minutes.

Add eggs one at a time, beating well after each addition. Use a wooden spoon, handheld mixer, or stand mixer with the flat beater attachment. The dough will transform into a thick, glossy, and smooth batter.

Bake for 30 minutes or until the puffs are tall, golden brown, and craggy on top. Do not open the oven while baking.

Remove puffs from the pan immediately and let cool on a wire rack. Serve warm and enjoy plain, with butter, jam, or a dusting of powdered sugar.