Use a whole garlic clove.
Cut off the top in one go.
Sprinkle a little salt and sugar on top and put the top back on.
Place it in the oven and roast for 1 hour at 200 degrees Celsius (392 degrees Fahrenheit) with fan.
Take it out of the oven and let it cool on a rack for 5-10 minutes before using.
Take the butter out of the fridge 30 minutes before preparing it, to make it easier to work with.
Rinse and dry the parsley. Chop it finely.
Put the parsley into a bowl with the butter.
Squeeze the tender garlic cloves out of their skins and into the bowl.
Add salt and pepper to the bowl and mix well with a fork to distribute the garlic evenly.
Season with extra salt/pepper and optionally lemon zest/juice to taste.