Combine cornmeal and next 7 ingredients in a large bowl. Stir together 3 egg yolks and buttermilk; add to dry ingredients, stirring just until moistened.
Beat 8 egg whites and cream of tartar at high speed with an electric mixer until stiff peaks form. Fold one-third egg white mixture into cornmeal mixture; repeat procedure twice using remaining egg white mixture and cornmeal mixture.
Brown butter in a 10-inch cast-iron skillet over medium-high heat. Place fillet in center of skillet; pour batter over top.
Bake at 400° for 20 minutes; place shrimp on top, and cook 10 additional minutes or until spoon bread is golden and shrimp turn pink. Serve immediately.