Preheat oven to 325 degrees. Gather all ingredcients. Butter a bread loaf pan (9" x 5").
Soften cream cheese. Add melted butter, olive oil, heavy whipping cream, and liquid stevia to the cream cheese. Mix with a stand or hand mixer - adding four eggs as you go. Add the baking powder and xanthan gum and mix to incorporate.
Add the protein powder, baking soda, salt, and cream of tartar to a sifter. Sift over the wet ingredients. Stir by hand, folding ingredients together. Do not over mix.
Pour into loaf pan and bake in oven for 45 minutes, or until the top is golden brown.
Remove from the pan and rest on sides alternating on a cooling rack until cooled.
Experiment with additional ingredients. We suggest cinnamon, nuts, garlic, asiago cheese, onion, or even chocolate.