Sweat the veggies. In a stockpot over medium heat, combine the olive oil, onion, thyme, paprika, Serrano pepper, a pinch of salt and a few grinds of black pepper. Stir with a wooden spoon and cook until the onion is tender but not browned, 5-8 minutes. Add the garlic and tomato paste, stirring to coat everything in the pot. Cook, stirring, over medium heat until the paste turns a deep red color, 8-10 more minutes.
Cook the tomatoes. Add the tomato chunks and bring to a simmer. Cook, stirring the tomatoes to ensure a bit of that moisture evaporates, but don’t burn them. Cook until the tomatoes are tender and the skins are peeling off, about 5 minutes.
Finish the soup. Add the chicken stock and bring to a boil, then reduce to a simmer and cook for just 10 more minutes. Remove the pot from the heat and, using tongs, remove the thyme sprigs. Using an immersion blender, blitz the soup in the pot, leaving a few chunks of tomato for texture. Return to low heat and slowly stir in the cream.* Serve warm.
*Add ground bottom of the bag tortilla chip crumbs to the soup at this point to make it extra-thick!