Preheat the oven to 425 degrees F.
Heat the milk and butter in a medium-large saucepan over medium-high heat. When the mixture simmers and the butter is melted, add the flour all at once and stir. Add the salt and pepper. Reduce heat to medium and stir for 1 to 2 minutes to dry the mixture out. Turn off heat and stir a bit more to cool slightly.
Add the eggs 1 at a time, beating well to incorporate each egg before adding the next. Stir in the cheese, mustards, and cayenne and mix until smooth. Transfer the mixture to a pastry bag with a large plain tip.
Pipe the mixture onto to a parchment paper-lined cookie sheet in rows of kisses, about 1- inch in diameter.
Smooth out any bumps with a fingertip dipped in flour.
(The recipe can be made to this point up to 8 hours in advance and refrigerated, or frozen for up to a week. Thaw at room temperature before baking.)
Bake for 10 minutes. Reduce the heat to 375 degrees F and continue baking until golden brown, about 8 to 10 minutes more.