Set your oven to preheat at 375 degrees Fahrenheit. Make sure both butter and milk are at room temperature before starting. Grate your cheddar cheese freshly for optimal creaminess.
Fill a large pot (minimum 3-quart capacity) halfway to three-quarters with water, add ½ tablespoon sea salt, and bring it to a boil. Add the elbow macaroni and cook until al dente following package instructions. Drain the pasta using a colander, turn off the heat, then place the cooked macaroni back into the pot.
Add the softened butter to the hot pasta and gently stir just until the butter melts; avoid stirring too much. Pour in the room temperature milk and mix lightly.
Sprinkle ½ teaspoon sea salt, ¼ teaspoon black pepper, and half (1½ cups) of the shredded cheddar cheese into the pasta mixture. Toss gently to combine; stir only enough to incorporate without waiting for the cheese to melt. Taste and adjust seasonings if needed.
Transfer the cheesy pasta mixture to a 2-quart casserole dish. Evenly spread the remaining 1½ cups of shredded cheddar cheese over the top without mixing.
Bake uncovered in the preheated oven for 10 minutes until the cheese on top is melted and slightly bubbly.
Remove the dish from the oven and give the mac and cheese a gentle stir. Allow it to sit for a few minutes before serving to reduce stringiness and enhance texture.
