Preheat oven to 350°F. Grease a 12-count non-stick muffin tin with butter or cooking spray.: As the kitchen warms, you should notice a faint toasty scent from the preheating coil. Setting the oven now ensures even heat so the muffins rise uniformly, forming gently domed tops. One reason this matters is that an oven that is too cool yields pale, dense muffins; too hot and edges overbake before the center sets. A common mistake is slipping in the batter before the oven is truly at temperature, which can flatten the rise, so always confirm the preheat indicator.
In a large mixing bowl, whisk together flour, sugar, baking powder, salt, and nutmeg.: Greasing the pan produces those golden, slightly crisp bottoms and makes removal effortless. When you brush melted butter into each cup, you can hear a faint slicking sound and see the glossy sheen. If you skip this step or under grease, muffins may cling and tear when removed. A tip is to use just enough butter so paper liners are unnecessary, but not so much that the bottoms become greasy.
Add warm milk, lightly beaten egg, and 5 Tbsp melted butter and stir until combined but still lumpy (DON'T over mix).: The dry ingredients should look evenly distributed, a pale, sandy mixture streaked with tiny flecks of nutmeg . Whisking aerates the flour and evenly disperses leavening, which promotes a consistent crumb. If baking powder is clumped it can create odd pockets of flavor or uneven rise, so break any lumps. Avoid overworking the mixture, which can develop gluten and make the muffins tough.
Divide the batter into your prepared pan using a spoon or ice cream scoop. Each cup will be about 1/3 full. Bake for 20-22 min or until golden at the edges and a toothpick inserted into the center comes out clean.: When the wet ingredients hit the dry, the batter will look like a thick, slightly shaggy paste dotted with tiny air pockets. The warmth of the milk helps the melted butter disperse evenly, and the beaten egg adds silkiness. Stir just until the streaks of flour disappear, because over mixing will cause gluten to form, leading to heavy muffins. Watch for a batter that clings to the spoon but still falls slowly; that indicates proper mixing.
For the topping, in a small bowl, mix together 1/3 cup of sugar with cinnamon. In a second small bowl, melt your remaining 3 Tbsp butter.: Dimpling each cup to the right level helps muffins bake with similar size and doneness. As you portion, you should see a glossy, slightly lumpy batter dropping into cups and settling into a smooth surface. Uniform scooping avoids some muffins finishing much earlier than others. A common misstep is overfilling, which makes the muffins dome and spill over, so stick to about one third full for this recipe.
Dip warm muffin tops briefly in melted butter, then dip/roll generously in cinnamon sugar. I like to coat the sides of the muffins with cinnamon sugar as well. Set them on a wire rack to cool.: During baking the tops will puff and faintly crack as air pockets expand. You will smell the cinnamon and nutmeg as the sugars caramelize. Check visually for a warm golden color at the edges and a toothpick emerging mostly clean. Pulling the muffins out too early can leave a gummy center, while leaving them too long will dry them out, so use the toothpick test and color cues together.
For the topping, in a small bowl, mix together 1/3 cup of sugar with cinnamon: The sugar and cinnamon should look like a slightly speckled sand, with the aroma of warm spice becoming apparent as you stir. This coating crystallizes into a crisp layer on the muffin top. If the cinnamon lumps or the sugar has hardened, break it up before rolling. Avoid using too coarse a sugar otherwise the texture will be overly crunchy compared to the tender crumb inside.
In a second small bowl, melt your remaining 3 Tbsp butter: The melted butter should be warm and glossy, not scorching. When you dip the muffin tops, the heat helps the sugar adhere and forms a subtle glaze. If the butter is too hot, it can melt the muffins slightly and make the coating slide off, so keep it warm to the touch, not boiling.
Dip warm muffin tops briefly in melted butter, then dip/roll generously in cinnamon sugar: The sensory joy here is the contrast between the warm, soft muffin and the crunchy, aromatic coating. The butter makes the cinnamon sugar stick and gives a slight shine. Roll the sides too if you like a fully coated treat. A frequent slip is coating muffins that have fully cooled, which prevents the sugar from adhering well; work while they are still warm.
Set them on a wire rack to cool: Cooling on a rack prevents trapped steam from making bottoms soggy, so the muffins retain their crisp tops and tender interiors. You will notice a gentle hiss as residual steam escapes, and the muffin tops will become slightly firmer as they cool. If you leave them in the pan, condensation can form and soften the crust, so transferring to a rack is key to preserving texture.