Bring salmon close to room temp (around 10mins out the fridge) and preheat oven to 190C/375F.
In a small mixing bowl combine butter, garlic, chives, parsley, dill, salt and pepper. Place to one side.
Place two large sheets of foil in a cross on a large baking tray (enough to be able to comfortably wrap the salmon). Place the salmon skin side down in the centre and pat the top with paper towels (makes it easier to spread the butter).
Use your spatula to spread the butter all across the top of the salmon. Fold in the foil to make a tent for the salmon. Try and make sure there's no gaps, but ideally ensure it's not touching the top of the salmon.
Place in the oven for 15-20mins, or until the thickest part of the salmon is almost cooked through. You want it a little undercooked at this point as it will continue cooking. I recommend peeking after 15mins and gently using two forks to see the doneness. If your salmon is particularly thin then check a few mins before. If it's thick, it may need slightly longer than 20mins.
Remove from the oven and crumple down the foil around the salmon. Spoon over any melted butter around it, then pop it under the grill and broil until the garlic starts lightly turning brown (5mins or so). The salmon should be cooked right through at this point.
Serve up right away (so it doesn't carry on cooking) with any leftover butter in the foil, alongside lemon wedges and extra seasoning if needed. Enjoy!