Preheat the oven to 400°F.
Combine the seafood stock, saffron, and pimenton in a small saucepan over medium heat and bring to a simmer; reduce the heat to very low and cover.
Lightly season the squid with salt and pepper. In an 8-inch cast-iron or other heavy skillet, heat 1 teaspoon of the olive oil over medium-high heat. When it shimmers, add the squid and cook, stirring frequently, just until the squid lose any translucence and exude their juices, 30 to 60 seconds. Transfer the squid to a plate and decrease the heat to medium.
Add the remaining 1 teaspoon of oil, then the red pepper flakes, scallions, and garlic and saute until the scallion starts to soften, another 2 to 3 minutes. Add the rice and cook until the grains are well coated with the pan mixture, 1 minute.
Pour in the hot broth and bring to a gentle boil. Decrease the heat to medium-low. Taste the liquid and add salt to taste, then let it continue to gently bubble, swirling the pan occasionally, for 8 to 10 minutes, or until the rice has swelled and absorbed much of the liquid; it should still be slightly soupy.
Stir in the squid and tomatoes. Transfer the pan to the oven and bake, uncovered, for 10 to 15 minutes, until the rice is al dente, or mostly tender but with a little resistance in the center.
Remove the pan from the oven, cover with a lid or aluminum foil, and let it sit for about 5 minutes, until the rice is tender. Uncover and return it to the stovetop over medium-high heat and cook for about 2 more minutes, to brown the bottom of the rice.
Spoon it out onto a plate, and eat, Don’t worry if it sticks. Just scrape it up and know that this is what the Spanish call soccarat, the crispy pieces that are considered a sign of a great paella.