Pour in the preheated wine and stir. Add garlic. Stir and allow the wine to reduce until it is almost dry. Pour in a ladle or 2 of preheated stock (about 1/2 cup) to barely cover the rice. From this point on, stir almost constantly. Adjust the heat so that the liquids are just above simmering.
Repeat the stock addition when the liquid reduces by two thirds. Stir. Repeat adding stock and stirring until the rice becomes creamy and al dente (about 20 minutes in total). Season the rice with salt, black pepper and cayenne pepper. Add the butter and Dijon mustard. Stir. Allow the rice to rest 5 minutes before serving.