HEAT oven to 400ºF. Spread tomatoes and peppers onto paper towels to drain. Meanwhile, cook and stir spinach and onions in dressing in skillet on medium heat until onions are tender and no liquid remains.
ROLL 1/2 the pastry on lightly floured surface to 12-inch square; press onto bottom and up side of greased 9-inch springform pan. Fill with layers of 1/2 each ham, spinach mixture, tomatoes, peppers and cheese. Repeat layers. Drizzle with all but 1 Tbsp. eggs.
ROLL remaining pastry to 11-inch square; place over ingredients in pan. Pinch edges of pastry together to seal. Brush top with reserved egg; cut slits in crust to allow steam to escape. Bake 55 min. or until golden brown. Cool 10 min.