Cook the bacon in a skillet over medium heat until crispy, about 5-7 minutes. It is ready when it smells amazing and turns a golden brown. Remove the bacon and leave the bacon fat in the skillet.
In the same skillet, melt the butter over medium heat. Stir in the flour and cook for about 1 minute, until bubbly and slightly thickened. This roux will help thicken your sauce.
Pour in the chicken broth slowly, followed by the heavy whipping cream. Whisk continuously to ensure a smooth consistency and to prevent lumps, stirring until fully blended.
Gradually sprinkle the grated Parmesan cheese into the sauce while whisking to combine. Continue stirring until the cheese melts completely and you achieve a creamy consistency.
Cook the spaghetti according to package instructions in a large pot of salted boiling water until al dente. Drain and reserve some pasta water, then add the drained spaghetti to the sauce. Toss to coat the pasta completely. If the sauce is too thick, add reserved pasta water a little at a time until the desired consistency is reached.
Crumble the crispy bacon over the coated pasta and gently stir it in. Reserve some bacon for garnish if desired.
Top with parsley for color and serve warm. Enjoy each creamy, cheesy bite along with the crunchy bacon.