Pat the chicken cubes very dry with paper towels, then toss with salt, pepper, and paprika. (Dry chicken = better browning. Wet chicken steams.)
Heat the olive oil in a large skillet over medium-high heat until shimmering.
Add the chicken in a single layer — don’t crowd the pan. Sear 3–4 minutes per side until golden and cooked through (165°F internal).
Push the chicken to the edges, drop in the butter and garlic, and cook 1 minute until fragrant.
Squeeze in the lemon juice, toss everything together, and shower with parsley.