Note: for this recipe, you want something super heavy, like a brick or a small baking dish filled with weights. I actually use a 6×6 inch baking dish or a plate and place two 8-pound weights inside of/on it!
Take the chicken and spatchcock it – meaning you want to cut out the backbone and flatten it. It’s intimidating at first, but once you do it, it’s easy! Here is a photo tutorial. Season the chicken all over with salt and pepper.
Heat a large cast iron skillet over medium heat. Add the butter and once it’s melted, place the chicken skin-side down in the skillet, tucking the wings underneath. Place the plate or dish on top and put your weight (brights/weights/cans/etc) on top of it. Cook for 25 to 30 minutes, until the skin is crispy and golden brown.
Remove the weights and plate and carefully flip the chicken over so it’s skin-side up. Replace the plate and weights and cook for 15 to 20 minutes more.
After 20 minutes, transfer the chicken to a plate. It’s okay if it starts to fall apart here! I like to leave all of the fat in the skillet unless there is a ridiculous amount (I like up to about 1/4 cup in the skillet). Whisk in the minced garlic and the flour to create a roux – you want the mixture to be golden in color and smell fragrant. Very slowly whisk in the stock and white wine, whisking the entire time until the mixture thickens. Stir in the frozen peas. Once the gravy has thickened, add the chicken back to the skillet, skin-side up. Cover with the plate and weights again and cook for 20 to 30 minutes, or until the internal temperature reads 165 degrees F.
To serve, pull the chicken apart (it should fall apart on its own!) and place it on a plate. Serve with the spring mashed potatoes and pan gravy.