When you don't preheat, you cook your food at a lower temperature as your oven heats up for the first 5-15 minutes, depending on the target temperature and your oven's strength. For forgiving foods, like a casserole, this may not affect you much—you'll just have to bake longer than the recipe says to.
Pat the turkey breast dry with paper towels, season both sides liberally with kosher salt and freshly ground black pepper.
Heat a large cast-iron skillet over very high heat. As it heats up, add 1/4 cup of duck fat to the skillet.
When the fat begins to shimmer, add the turkey breast, skin-side down, and cook until dark golden brown. It will take 3 to 5 minutes.
Remove the skillet from heat, and remove the turkey from the skillet. You can put it on a plate.
Stir 2 tablespoons of unsalted butter into the pan juices.
Arrange 1 bunch of thyme branches in the skillet to make a bed for the turkey.
Place the turkey, seared-side-up, on the thyme and sprinkle 4 cloves of smashed garlic around the sides.
Basting is the process of brushing, pouring, or spooning liquid over a food to make it moist and juicy from top to bottom and to give it a wonderfully golden look when cooked.
Get the juices in the pan over the turkey until it’s entirely covered.
Transfer the skillet to the oven.
Roast until meat thermometer inserted into the thickest part of the breast without touching bone registers 155°F. It will take about one hour. Baste every 15 minutes.
While the turkey roasts, let’s prepare the green onion puree.
In a medium saucepan, heat 1/2 cup of vegetable stock over medium-high heat.
Trim the ends off, then roughly chop 1/2 pound of green onions.
Pour the chopped green onions into vegetable stock. Keep the saucepan on medium-high and simmer until the green onion becomes tender. This will take about 5 minutes.
Using a slotted spoon, transfer the green onions to a blender, saving the liquids in the saucepan.
Blend on high until very smooth, about 5 minutes. Add a splash of cooking liquid if necessary to help the blender puree.
Add the cream cheese and blend for 2 more minutes. Season with salt to taste.
Once the meat thermometer registers 155°F, baste once more and transfer the turkey to a platter.
Let the turkey rest for at least 20 minutes before slicing and serving.
Slice the turkey breast across the grain and serve with green-onion puree.
Enjoy!