Heat oil in a skillet, sauté onion, garlic, carrots, and celery until soft (or toss them raw into the crockpot if lazy).
Add lentils, tomato paste, broth, thyme, rosemary, salt, and pepper. Stir well and transfer to the crockpot.
Cover and cook on low for 4 hours or high for 2.
Meanwhile, steam cauliflower until fork-tender (roughly 10 minutes).
Blend cauliflower with almond milk, nutritional yeast, vegan butter, garlic, and salt until creamy.
Once filling is ready, spread cauliflower mash on top.
Cover again and cook on warm for 15 minutes so everything gets cozy together.
Garnish with parsley, serve hot, and pretend it took way more effort.