Preheat the oven to 325°F (160°C).
Grease and flour a bundt pan.
In a large bowl, cream together the softened butter and cream cheese until smooth.
Gradually add in the sugar and beat until fluffy.
Add the eggs one at a time, mixing well after each addition.
In another bowl, whisk together the flour and baking powder.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Pour the batter into the prepared bundt pan and smooth the top.
Bake for 60-75 minutes, or until a toothpick comes out clean.
Allow to cool in the pan for 10 minutes, then invert onto a wire rack to cool completely.