Preheat the oven to 180°C/356°F and place the rack one down from the center.
Cook the aromatics: Heat a large skillet on medium heat and add the oil. Once the oil is hot, cook the onion until shimmering (2 to 3 minutes) add the garlic, mix it in.
1 onion, diced, 2 small garlic cloves, minced, 2 Tbsps. olive oil
Vegetables: Add the vegetables, except the spinach. If the heat is too high, lower it to medium because the vegetables need to soften for at least 15 minutes.
1 eggplant, diced, 1 bell pepper, large, any color, chopped, 1 carrot, sliced, 2 celery stalks rinsed and sliced, 2 to 3 zucchini, cubed
As they cook, you will use a wooden spoon to move them from one side to the other without smooshing them up. We are trying to maintain the shape, not mash them. This movement will aslo help them from sticking.
Seasoning: Add the vegetable spice, salt and pepper and 1 teaspoon of butter as soon as you see the vegetables are starting to change color. Try not to add any seasoning when you just add the veggies to the pan, give them a chance to heat up on a low sizzle and as they turn a deeper golden color, that's when you season. salt & pepper, 2 Tsps vegetable seasoning, 2 Tsps. butter
Tomatoes: Add the canned tomatoes and half the passata and cook on medium-high heat (gentle simmer). Add a sprinkle more dried herbs/vegetable spice.
700 ml tomato passata, 410 grams canned chopped tomato
Spinach: Add baby spinach and/or fresh herbs (the herbs are completely optional)
200 grams baby spinach, 1 cup chopped mixed herbs, optional
Remaining butter: As the sauce thickens, roughly 2 to 3 minutes, add the remaining teaspoon of butter (for creamy richness) and chopped herbs.
2 Tsps. butter