Season chicken breasts on both sides with salt and black pepper.
In a small bowl, whisk together honey, Dijon mustard, whole-grain mustard, minced garlic, and dried thyme.
Heat olive oil in a large skillet over medium-high heat.
Add chicken breasts to the skillet and sear for 5 to 7 minutes per side until golden brown and the internal temperature reaches 165 degrees Fahrenheit.
Reduce the heat to low and pour the honey mustard mixture over the chicken.
Simmer for 2 to 3 minutes, frequently spooning the sauce over the chicken until the glaze has thickened and coated the meat.