Place the butter into a medium sized bowl and mix to soften. Use a garlic crusher to crush each of the cloves of garlic into the bowl with the butter. Mix to combine.
Fold the parsley between your fingers and use a sharp knife to finely chop it. Add to the bowl with the butter and garlic. Mix everything together until well combined.
Use a bread knife to slice the loaf of bread ¾ of the way through, leaving the bottom still together. Using a butter knife spread a generous amount of the garlic butter on each slice of bread.