In medium bowl, stir together all Cupcake ingredients except butter, eggs and eggnog. In large bowl, beat 1/2 cup butter until creamy, about 1 minute. Add flour mixture all at once; beat until mixture resembles crumble topping. Add 2 eggs; beat about 30 seconds. Scrape side and bottom of bowl well; beat 1 minute longer. Batter should be light in color and a bit fluffy. Scrape bowl; gently beat in 1/2 cup eggnog just until combined and batter is silky and smooth. Divide batter evenly among muffin cups.