1-First, prepare all ingredients by mincing the garlic, measuring out the liquids, and seasoning the chicken breasts evenly with salt and pepper. This sets the stage for smooth cooking and keeps things organized in your kitchen.

2-Second, heat the olive oil in a large skillet over medium-high heat until it’s shimmering, then add the seasoned chicken breasts. Cook for about 5-6 minutes on each side until they’re golden brown and fully cooked, then remove them and set aside to rest.

3-Third, in the same skillet, lower the heat to medium and add the unsalted butter. Once it’s melted, stir in the finely chopped shallot, minced garlic, 1/2 teaspoon salt, and 1/4 teaspoon pepper, cooking until the shallot softens, which takes about 1 minute.

4-Fourth, add the flour to coat the shallots and garlic evenly, cooking for another minute to build a base for the sauce.

5-Fifth, gradually stir in the half-and-half or milk and chicken broth, scraping up those tasty browned bits from the pan. Bring it to a boil, then reduce to a simmer for a few minutes until it starts to thicken.

6-Sixth, return the chicken to the skillet and let it simmer in the sauce for 3 to 4 minutes, ensuring everything melds together perfectly.

7-Seventh, stir in the lemon juice for that fresh burst, then garnish with parsley and lemon slices before serving. For adaptations, check the dietary substitutions section to tweak for vegan or low-calorie versions.