Cut broccoli florets into bite-sized pieces. Core Roma tomato and cut into 1/4" dice. Mince garlic. Peel and halve shallot. Slice half the shallot into thin strips (julienne) and cut other half into a fine dice. Stem, seed, and cut red bell pepper into 1/2" dice. Rinse chicken breasts, pat dry, and season with 1/2 tsp. salt and a pinch of pepper.

Heat 2 tsp. olive oil in a medium pan over medium-high heat. Place chicken breasts in hot pan and cook 3-5 minutes per side, or until golden brown. While chicken sears, place broccoli, red bell pepper, julienned shallots, and half the garlic on one half of prepared baking sheet. Toss vegetables with 2 tsp. olive oil, 1/4 tsp. salt, and a pinch of pepper. Roast 5 minutes.

Remove baking sheet from oven and transfer seared chicken to other half of baking sheet. Return baking sheet to oven and bake 10 minutes, or until chicken reaches a minimum internal temperature of 165 degrees.

While chicken cooks, heat 1 tsp. olive oil in same pan used to sear chicken (no need to wipe clean) over medium-high heat. Add remaining garlic and finely diced shallots to hot pan and cook 30 seconds, or until fragrant. Add evaporated milk and cook 1 minute while stirring. Stir in shredded cheddar and cook an additional minute, or until sauce thickens. Remove from burner and season with a pinch of salt and pepper. Stir in Roma tomatoes (reserve a pinch for garnish).

Place a chicken breast on a plate next to a serving of roasted vegetables. Top chicken with sauce. Garnish with reserved diced tomatoes and red pepper flakes (to taste).