Prepare cake pan with parchment paper on bottom, and butter the sides (or spray with PAM) 8" cake pan is the best option
Combine sugar and eggs in a large bowl or stand mixer. Beat with mixer until fully combined and fluffy
Mix the Pane Degli Angeli or baking powder with the flour, once mixed add it to the egg and sugar mixture.
Slowly add in the soft butter, mix until all ingredients have been fully combined, slowly stir in the yogurt
Cut the orange into small pieces, LEAVE the peel. (only thing that should be removed are seeds) (1 inch cubes apprx.) Place into a food processor, and pulse until orange is almost pureed, but not completely.
Add pureed orange to cake batter, and stir until evenly combined
Bake for between 50-60 minutes, depending on your oven. Internal temperature of apprx. 210F
Allow to cook for about 20 minutes, dust with powdered sugar.