The best palak paneer I have had is from a restaurant called Moti Mahal, not far from where we grew up in Delhi. I had to try a few times before I developed this version that is quite close to the taste I remember from my childhood.

Ingredients
Spinach leaves 1/2 kg, washed, steamed and puréed
Onion 1 medium, sliced fine
Garlic 6 cloves, sliced in half
Ginger 1” piece, julienned
Tomato 1 medium, sliced fine
Red chilli powder 1/2 tsp
Turmeric powder 1/2 tsp
Coriander powder 1/2 tsp
Salt to taste
Water 3 cups
Paneer or cottage cheese 200 g, cut into cubes
Oil 4 tbsp
Method
Heat the oil in a heavy bottomed pan and fry the paneer cubes till they turn a light crispy brown. Take them out with a slotted spoon and keep aside.
Add onion slices to the same oil and fry till they turn golden and translucent. Scrape the paneer bits as you fry the onions.

Add the puréed spinach and stir well.

Add the water, salt, red chilli powder, turmeric powder and coriander powder.
Add the garlic. Use the smaller Indian garlic instead of the plumper Chinese ones. They have more flavour.

Add the tomato slices.

Reduce the heat and cook covered for 20 minutes.
Add the fried paneer cubes and continue to cook till the gravy thickens.

Garnish with the julienned ginger and serve hot with rice, naan, puris or paranthas.