Pat the chicken breasts dry with paper towels. Season both sides with salt, black pepper, garlic powder, and dried thyme.
Heat olive oil in a large skillet over medium-high heat until shimmering.
Add the chicken breasts to the skillet and cook for 6-7 minutes on one side without moving, until golden brown.
Flip the chicken breasts and cook for an additional 6-7 minutes, or until the internal temperature reaches 165°F (74°C). Remove chicken from skillet and set aside to rest.
In the same skillet, reduce heat to medium and add butter. Once melted, add minced garlic and sauté for 30 seconds until fragrant.
Add red bell pepper, zucchini, yellow squash, and broccoli florets to the skillet. Stir to combine.
Pour in the chicken broth, cover the skillet, and cook the vegetables for 5 minutes, stirring halfway through, until tender but still crisp.
Remove the lid and cook for another 2 minutes to evaporate excess liquid.
Slice the rested chicken breasts and serve alongside the sautéed vegetables.