Add olive oil to a dutch oven or deep saucepan over medium heat.
When hot, add pancetta, onion, carrot, and celery and cook until they're beginning to soften and brown, about 5 minutes. Add garlic and cook until fragrant, about one minute.
Add ground beef and ground pork to saucepan and cook while breaking up with a wooden spoon, about 5 minutes, until meat is starting to brown.
Add white wine and using a wooden spoon, scrape up any brown bits on the bottom of the pan. Simmer for about 5 minutes to reduce.
Stir in tomato paste and cook for one minute.
Add the tomatoes, crushing them with your hands as you do. Stir in the thyme and parmesan rind, if using. Bring mixture to a simmer and then reduce heat to low. Cover the saucepan and let simmer for about 2 hours, stirring occasionally, until sauce is nice and thick.
When sauce is almost done cooking, bring a large pot of salted water to a boil and add gnocchi. Stir lightly to prevent sticking and cook for about 2-3 minutes, until gnocchi float to the top of the water. Note that if your gnocchi are frozen they may require 1-2 minutes extra cooking time. Drain.
While gnocchi is cooking, remove parmesan rind and thyme sprigs from sauce. Stir the milk in and and let simmer for another 5 minutes. Taste sauce and add salt and pepper according to your tastes (I usually add 1 teaspoon of each).
Serve the pork bolognese over the gnocchi or toss the gnocchi in the sauce. Top with grated parmesan, chopped basil, and red pepper flakes if desired.