Cut the chicken into bite-size pieces. Dry it a little with paper towels so it browns better.
Heat a large skillet over medium heat. Add the olive oil.
Add the chicken in a single layer. Don’t move it for a minute or two. Let it get some color.
Flip the chicken pieces and season with salt and black pepper.
Lower the heat slightly. Add the butter and let it melt around the chicken.
Add the garlic and stir. Cook for about 30 seconds, just until fragrant.
Sprinkle in paprika and chili flakes if using. Stir everything together.
Taste and adjust salt or butter if needed.
Turn off the heat. Add lemon juice if using and let the chicken rest for 1–2 minutes.
Serve warm, spooning the garlic butter sauce over the chicken.