I start by heating my oven to 400°F and lining a large baking sheet with parchment paper. This step keeps cleanup easy and stops the chicken from sticking. I make sure the parchment doesn't hang over the edges of the pan since it'll go under the broiler later.
Next, I lay the chicken breasts evenly spaced across the baking sheet. Giving them a little breathing room helps them roast instead of steam. I try to use breasts that are roughly the same thickness so they all cook at the same pace.
In a small bowl, I whisk together the Herbes de Provence, minced garlic, olive oil, maple syrup, lemon zest, lemon juice, salt, and pepper. I like to crush the herbs a bit between my fingers first, which really wakes up their flavor before they hit the sauce.
I pour about half of the sauce over the chicken breasts and slide the pan into the oven. I let it bake alone for around 20 minutes, until it's almost cooked through but not quite finished yet.
While the chicken bakes, I trim the woody ends off the asparagus by snapping them where they naturally break. I toss the trimmed spears with the remaining sauce so they're ready to go the moment the chicken comes out.
Once the chicken is nearly done, I pull the pan out and switch my oven to broil. I arrange the asparagus around the chicken, pour over any extra sauce, and tuck a few lemon slices on top of everything.
I slide the pan back in under a low broil for about 10 minutes, watching closely until the chicken is golden and cooked through and the asparagus turns crisp-tender. Broiling browns everything beautifully in just a few minutes.
Finally, I pull the pan out and serve everything right away while it's hot. The lemon slices soften into the dish and add such a pretty, restaurant-style finish.