In a large pot, heat 2 tbsp. oil over medium-high. Add the beef; season with salt and pepper. Cook, stirring often and breaking up with a spoon, until browned, about 5 minutes. Add the celery, shallots and garlic; season. Cook, stirring often, until vegetables soften, about 5 minutes. Stir in the tomato paste and 3 tsp. rosemary and cook, stirring often, until fragrant, about 3 minutes.
Stir in the stock and pomegranate juice. Simmer the ragu over medium-low, stirring often, until the liquid is thickened and saucy, 25 to 30 minutes; season.
In a large pot of boiling, salted water, cook the pasta to al dente; drain. Return to the pot and stir in the remaining 1 tbsp. oil; season. Divide the pasta among bowls; top with the ragu, ricotta and remaining rosemary.