Generously grease and flour a 15-cup bundt pan.

In a large bowl, beat butter and cream cheese until fluffy, 3-4 minutes. Add sugar, 1 cup brown sugar, and salt. Beat on high speed for 8-10 minutes, stopping to scrape sides of bowl. Add eggs, one at a time, beating well after each addition.

Mix in vanilla, flour, 1 teaspoon pumpkin pie spice, and baking powder until smooth.

In a small bowl, stir together pecans, remaining 1/3 cup brown sugar, and remaining 2 tablespoons pumpkin pie spice.

Spoon half of the batter into the prepared pan. Sprinkle pecan mixture over batter. Top with remaining batter.

Using a knife, pull blade back and forth through batter to swirl. Smooth the top with of the batter with an offset spatula or the back of a spoon.

Place the cake in a cold oven. Set temperature to 300 degrees and bake until a wooden pick inserted near center comes out clean, approximately 1 hour and 20 minutes.

Let cool in pan 10 minutes before turning on to a wire rack to cool completely. Slice and serve with caramel sauce, if desired.