Heat half the butter and half the oil in a large nonstick pan over medium-high heat.
Add onion, garlic, carrots, celery and saute until onion is translucent and garlic is fragrant.
Transfer this to slow cooker.
Heat remaining butter and oil in the same nonstick pan over medium-high heat.
Add beef and cook, breaking it up, until browned.
Transfer to slow cooker as well.
In the same nonstick pan, add red wine.
Bring to simmer and scrape all the brown bits off the bottom of the pan.
Then, pour this mixture into the slow cooker too.
Add crushed tomatoes, tomato paste, milk, Italian seasoning, salt, pepper, sugar, crushed bouillon cubes, red chili flakes, bay leaf.
Mix until combined.
Cover and cook on low heat for 6 hours.
Discard bay leaf.
Garnish with parsley and enjoy!