These rolls are as fluffy as can be and so tasty with a touch of sweetened butter.
With a wooden spoon, stir warm milk, warm water, and sugar in the bowl of an electric mixer. Sprinkle yeast on top; let stand until foamy, about 10 minutes.
Fit mixer with the dough hook. Add 3 egg yolks, the salt, butter, cornmeal, and flour to yeast mixture. Mix on low speed. Raise speed to medium; mix until dough is tacky but doesn't stick to fingers, 6 to 8 minutes. Transfer to a large oiled bowl, and loosely cover with plastic wrap.
Let dough rise in a warm spot until doubled in bulk, about 30 minutes.
Preheat oven to 400 degrees. Butter 12 cups of a standard muffin tin. On a lightly floured work surface, divide dough into 12 equal pieces. Roll into balls; transfer to tin. Loosely cover with plastic wrap. Let dough rise until doubled in bulk, about 20 minutes.
Whisk together remaining yolk and tablespoon milk; brush over dough. Bake until just golden, 15 to 20 minutes.
Meanwhile, make honey butter: Put butter in the bowl of an electric mixer fitted with the paddle; mix on medium-high speed until smooth. On low speed, add honey in a slow, steady stream. Mix in salt. Serve with muffins.