Before you start make sure to soak paneer in warm water for 20 minutes. This is especially important if you are using frozen paneer or the ones sold in stores in US. If using fresh paneer, you can skip this step.
To a large pan/kadai, add 1 tablespoon oil on medium heat. To that add your quartered onions (petals separated) and cut bell peppers. Sauté them for 3 to 4 minutes until they soften a little. Then remove them on a plate and set aside.
To the same pan, now cumin seeds and let them sizzle. Then add store bought marinara sauce (I love using Rao's brand). Add around 1 & 1/2 to 1& 3/4 cup of marinara sauce. Mix it well.
Then add the tomato paste, coriander powder, Kashmiri red chili powder (for color), garam masala, red chili powder, cardamom powder, sugar and salt to taste. Mix and cook the spices for 30 to 60 seconds.
Add the butter (I recommend using Amul butter) and cream. Mix until it's combined and the butter melts.
Now add crushed kasuri methi and mix. Add in the paneer cubes along with the sautéed onions and peppers.
Mix everything together, garnish with cilantro. Your 15 minute Kadai Paneer is now ready to be served! Enjoy with naan!
Notes
Use good quality marinara sauce for best results. I recommend the brand Rao's or Lucini.
The sauce already has salt in it so adjust salt levels to taste.
To make it spicier, you can add some sliced green chilies or add more of the red chili powder.
The cream, butter and sugar helps balance the tartness of tomatoes so do not skip on those.
You can add more butter or cream to make it richer/creamier.