In a large bowl, combine brown sugar, smoked paprika, garlic powder, onion powder, kosher salt, and black pepper. Set aside for chicken.
Cut the chicken breasts into 1-inch cubes, removing any fat or grizzle as needed.
Add the diced chicken to the mixing bowl with the spice blend andtoss to coat the chicken evenly with the spice rub.
Heat the olive oil in a large cast-iron skillet over medium-high heat, until shimmering (~1 minute). Reduce the heat to medium and add the chicken pieces in a single layer. Let cook, undisturbed, until the bottom is golden brown, about 3 minutes. Flip and continue to cook for 2 minutes longer, or until nearly cooked through.
Add the butter to the pan and cook, stirring often, for 1-3 minutes, until the chicken is coated with melted butter and reaches an internal temperature of 165˚F. Top with parsley if desired.
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Notes
*Note on Size of Chicken Bites* By cutting the chicken into 1-inch pieces they have more surface area for the delicious rub to impart flavor and cook faster. Feel free to cut into 1 ½ inch pieces, keeping in mind they may need to cook 1-2 minutes longer. For Chicken Thighs: Remove any fat or grizzle before cubing into 1-inch pieces and cook for 1-2 minutes longer.Smoked Paprika: Feel free to replace with regular paprika.Dairy-Free? Use your favorite non-dairy butter to finish the chicken bites.Storage: Store leftover chicken bites in an airtight container in the refrigerator for up to 3 days. If making a wrap or salad, there is no need to reheat the chicken bites. But if you would like them toasty, it is best to quickly reheat in a in a hot skillet with a bit of oil. This will keep them crispy and moist.