Preheat oven to 400°F.
On a rimmed baking sheet lined with foil, arrange tomatoes, garlic and thyme. Drizzle with EVOO and toss to coat. Roast 30 minutes until the tomatoes burst. Slide everything into a food processor and purée.
Heat a deep skillet or Dutch oven over medium-high heat. Add olive oil, 2 turns of the pan, and beef. Season with salt and pepper, and brown and crumble. Add onions and cook until soft; add stock. Add tomato purée and stir in parsley, basil and milk. Simmer 30-40 minutes to thicken.
Bring a large pot of water to a boil, add salt and pasta, and cook to al dente. Reserve 1 cup starchy water then drain pasta and return it to the hot pot. Toss pasta with starchy water, half the sauce and a drizzle or two of EVOO to coat.
Serve pasta topped with more sauce and some Grana Padano or Parmigiano-Reggiano cheese.