Preheat oven to 400 degrees. Line a square baking dish with foil or parchment paper to avoid mess.
Use a pairing knife to cut off all the green tough leaves that lead to the stem. Cut off the stem. Use the pairing kniife to cut out a little bit of the core at the bottom. (This isn't madatory.)
Use your hands to rub the cauliflower all over with two tablespoons olive oil. Make sure to get the bottom and all the crevies.. Sprinkle generously with 1/2 teaspoon salt (tops, sides, and bottom) and a little bit of pepper.
Add the cauliflower stem-side down to the prepared baking dish. Pour 1/4 cup of chicken stock on the bottom of them pan. Cover with foil and bake for 15 minutes.
While the cauliflower is in the oven, add the remaining olive oil, onion powder, garlic powder, 1/4 teaspoon salt, and coriander to a small bowl. Mix until combined. It just be in-between a sauce and a paste.
When the cauliflower has steamed for 15 minutes, take it out of the oven and remove the foil. Turn the heat up to 450 degrees on the oven. Brush all over with the rub. Pop back into the oven and bake another 25-30 minutes until the cauliflower is easily pierced with a knife and the top is super crisp and brown. (If you have a very large cauliflower, it may take more time, if you have a small one, less time.) If you want it a little more charred, turn the broiler on the last minute or two of cooking.
While the cauliflower roasts, make the chimichurri. Ardd the Calabrian chilis, oil, lemonn zest, lemon juice, capers, cilantro, and remaining 1/4 teaspoon salt to a small bowl. Stir. Season to taste with salt and pepper.
As soon as the cauliflower comes out of the oven, drizzle with the chimichurri. Sprinkle with pine nuts and feta cheese. Serve.