Heat the butter over a medium heat and gently fry the garlic for a minute, it shouldn't brown at all so lower heat if you need.
Pour in the cream and bring to a very gentle simmer (lower the heat if you need, it shouldn't be boiling).
Add the parmesan in 2 or 3 separate lots, mixing and letting it melt in between each addition.
Add the pepper and lemon juice and mix in quickly.
Add the bacon back in to the sauce.
Add ¼ cup of pasta water and let it gently simmer for a 2 - 3 minutes to thicken slightly.
Add the cooked pasta, toss and let it gently bubble away for a minute or two. Add more pasta water if you need to loosen. It should be really saucy in the pan as it will dry up when taken off the heat.
Mix the chopped parsley through.
Slice the chicken then serve the pasta with the chicken pieces on top or tossed through.
Little optional step is to finish the dish with some lemon zest and of course some extra parmesan if you wish.