Preheat and prep: Heat your oven to 425°F (220°C). Line two sheet pans with parchment for easy cleanup.
Chop the veggies: Halve the cherry tomatoes.
Cut zucchini and bell pepper into bite-size pieces. Slice the red onion into wedges. Break broccoli into small florets.
Season the veggies: Toss all veggies with 1–2 tablespoons olive oil, a big pinch of salt, and black pepper.
Spread them out on the sheet pans. Keep tomatoes grouped so they don’t roll everywhere.
Roast: Roast veggies for 18–22 minutes, stirring once, until the edges are golden and the broccoli is tender with a little char. Tomatoes should be jammy.
Cook the grains: While veggies roast, prepare your base.
Cook quinoa, rice, or farro according to package directions, or warm leftover grains. Fluff with a fork and season with a pinch of salt and a squeeze of lemon.
Season the chicken: Pat chicken dry. Cut into 1-inch pieces or thinly slice.
Season with salt and pepper.
Sear the chicken: Heat a large skillet over medium-high. Add a drizzle of oil. Cook chicken in a single layer, 3–5 minutes per side, until browned and cooked through.
Work in batches if needed so it browns instead of steams.
Toss with pesto: Reduce heat to low. Add 1/2 cup pesto to the skillet and toss to coat. If it looks thick, add a splash of water or a squeeze of lemon to loosen.
Taste and adjust salt.
Warm the mozzarella gently: Remove skillet from heat. Stir in mozzarella pearls, letting them soften and get a little melty from the residual heat. Don’t overheat or they’ll turn rubbery.
Build the bowls: Add a scoop of grains or a handful of spinach to each bowl.
Top with roasted veggies and pesto chicken with mozzarella. Spoon over any extra pesto from the pan.
Finish and serve: Add a squeeze of lemon, a sprinkle of Parmesan, red pepper flakes for heat, fresh basil, or a light drizzle of balsamic glaze. Serve warm or at room temperature.