Preheat oven to 320f and prepare a loaf pan with parchment paper and cooking spray.
In a large bowl whisk together flour, protein powder, sweetener, baking soda, baking powder, and salt.
In a second bowl mix together greek yogurt, eggs, lemon zest, lemon juice, vanilla, melted butter, and melted coconut oil. Now pour wet ingredients into dry and fold together. Be sure to not over mix.
Pour batter into loaf pan and place in the oven for 55-65 minutes. Be sure to check centre of the loaf with a wooden skewer. You want it to come out clean! That means it's done!
Allow the loaf to cool on a rack and this is the perfect time to whip up the icing. In a bowl mix together powdered sugar, protein powder, milk, and lemon juice. Drizzle the icing over the loaf, pour a cup of tea and enjoy!