Homemade Bolognese sauce by Chef John is hearty and intensely flavorful with mirepoix and ground beef simmered in plum tomatoes, milk, and white wine.
Melt butter with olive oil in a large saucepan over medium heat. Add onion, celery, carrot, and 1 pinch salt; cook and stir until onion turns translucent, about 5 minutes.
Stir ground beef into vegetables; cook and stir until meat is crumbly and no longer pink, about 5 minutes. Season with 1 1/2 teaspoons salt, nutmeg, cayenne pepper, and black pepper.
Pour milk into ground beef mixture and bring to a simmer. Cook, stirring frequently, until most of the milk has evaporated and the bottom of the pan is still slightly saucy, about 5 minutes.
Increase heat to medium-high and pour in white wine; cook and stir until wine has mostly evaporated, about 5 minutes.
Pour tomatoes with juice into a large mixing bowl; crush them with your hands until they resemble a chunky sauce. Pour tomato mixture into ground beef mixture; fill the tomato can with 2 cups water and stir into sauce. Bring to a boil.
Reduce heat to low and simmer, stirring often, until mixture cooks down into a thick sauce, at least 3 hours but preferably 4 to 6 hours. Skim fat from the top of sauce if desired. Add more water if sauce is too thick. Taste and adjust seasonings before serving.