HEAT oven to 375ºF.
PLACE tomatoes, cut-sides up, on foil-covered rimmed baking sheet sprayed with cooking spray. Bake 45 min. or until lightly browned. Top each with 1 Tbsp. cheese mixture; bake 15 min.
MEANWHILE, toss spinach with dressing.
SPREAD toast slices with ricotta; top with spinach and tomatoes.
