Add the walnuts and sundried tomatoes to the bowl of your food processor and pulse until broken down and crumbly, without pureeing. Transfer to a small bowl and set aside.
Now add the onion, garlic, and cauliflower florets to your food processor and gently pulse until chopped, but do not overprocess. Keep the pieces chunky for a hearty sauce and the best texture, working in batches as needed. Transfer each batch to a sauce pot or deep nonstick skillet.
Sauté the veggies over medium-high heat, stirring occasionally, until reduced, approx 5-7 minutes. You should not need water or oil, as the veggies will release moisture. But if anything is sticking, add 1-2 tablespoons of water.
Then add all the remaining sauce ingredients: walnut and sundried tomato mixture, tomato sauce, broth, lentils, and all the seasoning. Simmer for 20 minutes, until the lentils are cooked and the sauce is thick. Taste for seasoning and add more if needed. Discard the bay leaves.
Meanwhile, bring a large pot of generously salted water to a boil, and cook your pasta according to package directions for 'al dente' pasta. Then serve the pasta with a generous scoop of the cauliflower bolognese sauce on top.
Notes
Do not overprocess the veggies. You want a chunky, hearty cauliflower bolognese sauce, so make sure to keep some texture.
Simmer the sauce for at least 20 minutes. Simmering allows the flavours to marry beautifully. If you have extra time, simmer even longer. The more it simmers, the more the flavours will amplify.
Add more broth if your sauce gets too thick. It should be thick and rich, but if you find it's getting too thick, add an extra half cup of vegetable broth.
Salt your pasta water! Be sure to add enough salt to your pot of water for the best results. Here’s a handy guide to help if needed.
Do not overcook your pasta. Follow the directions for ‘al dente’ pasta. Al dente translates as 'firm when bitten'. If your package does not include directions for ‘al dente’ undercook your pasta by 1-3 minutes. ‘Al dente’ pasta is still firm once cooked, and not mushy. This gives you optimal texture.
For nut-free, use sunflower seeds or pumpkin seeds to replace the walnuts with similar results.
For lower calories, enjoy a smaller portion of pasta with a larger portion of the cauliflower bolognese sauce. OR use zucchini noodles, carrot noodles, or spaghetti squash.
For a thinner sauce, add more broth and/or tomato sauce.
Leftover cauliflower bolognese sauce will keep refrigerated for up to 5 days in a sealed container, or freeze it airtight for up to 3 months.