Preheat oven to 325°. Beat first 2 ingredients at medium speed with a heavy-duty electric stand mixer until creamy. Gradually add sugar, beating at medium speed until light and fluffy. Add eggs, 1 at a time, beating just until yellow disappears.
Sift together flour and next 2 ingredients; add to butter mixture alternately with milk, beginning and ending with flour mixture. Beat at low speed just until blended after each addition. Stir in lemon zest and next 2 ingredients.
Pour batter into a greased and floured 10-inch (16-cup) tube pan.
Bake at 325° for 1 hour and 15 minutes to 1 hour and 30 minutes or until a long wooden pick inserted in center of cake comes out clean. Cool cake in pan on wire rack 15 minutes.
Meanwhile, prepare Lemon Curd Glaze. Remove cake from pan to wire rack; gently brush warm glaze over top and sides of cake. Cool completely on a wire rack (about 1 hour). Garnish, if desired.
Try This Twist! Lime Curd Pound Cake: Omit lemon extract. Substitute lime zest for lemon zest and Lime Curd Glaze for Lemon Curd Glaze. Proceed with recipe as directed.