Preheat oven to 350°F (175°C). Grease a bundt pan or donut pan thoroughly.
In a large bowl, whisk together flour, sugar, baking powder, nutmeg, and salt.
In a separate bowl, whisk milk, melted butter, eggs, and vanilla until smooth.
Pour wet ingredients into dry ingredients and gently fold until just combined. Don't overmix.
Pour batter into prepared pan. Bake for 35-40 minutes for bundt pan, or 12-15 minutes for donut pan, until toothpick comes out clean.
Cool in pan for 10 minutes, then turn out onto wire rack to cool completely.
For glaze: Whisk all glaze ingredients until smooth. Adjust consistency with more milk or powdered sugar as needed.
Drizzle glaze over completely cooled cake. Add sprinkles or decorations while glaze is wet.