Preheat oven to 350 degrees F. Grease 8 1/2 -by 4 1/2-by 2 3/4-inch loaf pan; line with aluminum foil 16 inches long, 5 inches wide. Grease bottom and sides. Pare carrots, cut into 1/4-inch cubes. Cover with boiling water in small saucepan and cook, covered, 10 minutes. Drain well; set aside. Wash red pepper; cut in half; discard ribs and seeds; cut into 1/4-inch cubes (1 1/2 cups); set aside. In hot butter in large saucepan, saute onion, stirring, about 5 minutes. Stir in spinach, half-and-half, 1 teaspoon salt, the sugar, dash pepper and nutmeg. Remove from heat. In large bowl, beat eggs slightly. Add bread crumbs and Swiss cheese; stir in spinach mixture, mixing well. Spread 1/3 spinach mixture in loaf pan. Layer with carrot. Layer with 1/3 spinach mixture. Layer with red pepper. Top with rest of spinach mixture. Place greased waxed paper over top of pan. Set pan in larger pan; pour 1 1/2 inches boiling water into larger pan. Bake 60 minutes, until knife inserted in center comes out clean (the edges will just be beginning to brown. TO MAKE THE CHEESE SAUCE: In small saucepan, slowly melt butter; remove from heat. Stir in flour, seasonings and milk until smooth. Bring to boiling, stirring, until thick. Reduce heat; add Cheddar; stir until smooth. TO SERVE: Cool loaf 20 minutes. Loosen edge with spatula. Invert onto warm platter. Top with sauce. Garnish with the red-pepper rings.