Pre heat oven to 325 degrees F
Oil and flour 10 inch tube pan
Put flour and baking powder in medium bowl and set aside.
In bowl of mixer cream the butter.
Add the sugar and mix until pale yellow and fluffy.
Add in the sour cream, mix until combined.
Add in the eggs, vanilla, orange juice and zest, mix until well combined.
With mixer on low slowly add in the flour mixture, mix until well combined.
Pour batter into tube pan and bake for 1 hour and 20 minutes.
Remove from oven and let cool completely.
Remove from pan.
GLAZE:
In bowl of mixer with paddle attachment add in the cream cheese and whip about 30 seconds.
Add in the sugar and mix until well combined.
Add in the vanilla, orange juice, orange zest and mix until all combined.
ASSEMBLY:
Place cake on cake plate or stand.
Spoon glaze onto top of cake and gently nudge towards the edges of cake with back of spoon so it drips down slightly.
If using, arrange orange slices on top and add sprinkles.