Weigh or lightly spoon flour into a dry measuring cup; level with a knife. Combine flour, cornmeal, baking powder, and salt in a medium bowl, stirring mixture with a whisk.
Place egg substitute, sugar, and oil in a large bowl; beat with a mixer at medium-high speed 1 minute or until well blended. Add thyme, rind, and juice; beat at low speed until combined. Add flour mixture; beat just until combined. Chop 1 tablespoon nuts; stir into batter.
Pour batter into a 9 x 5–inch loaf pan coated with cooking spray. Sprinkle evenly with remaining 1 tablespoon whole nuts. Bake at 325° for 30 minutes. Remove pan from oven (do not turn oven off). Drizzle butter evenly over batter. Bake an additional 20 minutes or until a wooden pick inserted in center comes out clean. Cool in pan 5 minutes on a wire rack; remove from pan. Cool completely on wire rack.