In a large Dutch oven, brown the ground beef, over medium-high heat, season with salt and pepper.
When the beef is cooked through, remove from the Dutch oven; set aside.
Add the butter and olive oil to the Dutch oven; when the butter has melted, add the thinly sliced onions.
Cover the Dutch oven; opening every so often to stir; the goal here is to caramelize the onions without burning; this should take around 25 minutes, depending on how hot the burner is.
When the onions have caramelized, remove from the pan; set aside.
Add the Arborio rice to the Dutch oven; stir around with a wooden spoon, letting the rice toast for a few minutes.
When the rice has some color, begin adding the beef stock; add one cup at a time; stir constantly, letting the rice get air and soak up the liquid.
Continue this process until the entire 32 ounces of beef stock has been used and the rice is tender.
Add the ground beef and onions back to the risotto; stirring until incorporated.
Remove the Dutch oven from the heat.
Measure in the milk and provolone; stir; sprinkle in the thyme.
Best if served warm.
