HEAT oven to 350ºF.
GRATE half the orange; discard grated orange half. Thinly slice remaining orange half.
BEAT cake mix, 1-1/2 cups sour cream, poppy seed, orange zest and 1 tsp. orange extract with mixer until well blended. (Batter will be thick.) Pour into 9x5-inch loaf pan sprayed with cooking spray.
BAKE 55 min. to 1 hour or until toothpick inserted in center comes out clean. Cool cake in pan 10 min.; remove from pan to wire rack. Cool completely. Transfer to plate.
BEAT cream cheese, almond extract and remaining sour cream and orange extract in medium bowl with mixer until well blended. Gradually beat in sugar; spread over top of cake. Garnish with orange slices.