Wash and chop the butternut squash, courgette, broccoli, leek and tomatoes into large pieces. Wash the raw spinaches and clean the garlic.
In the slow cooker, add the olive oil, garlic (each clove cut in half), spinaches and all of the chopped vegetables. Cover and turn on the sear function of the slow cooker and cook the vegetables for 15 minutes.
Then add the crushed tomatoes and add some water in the empty can of tomatoes, swirl and pour the liquid into the slow cooker. Cover, switch the slow cooker function to high, and cook for 4 hours.
After 1 hour add all the spices and tomato paste, cover and continue to cook
When the sauce is nearly ready, cook the pasta according to the package instructions.
Add the cooked pasta and stir until everything is well combined. Taste and adjust seasoning as needed. Top with fresh basil, finely chopped, and serve immediately.