Preheat oven to 350°F (175°C). Line a loaf pan with parchment paper or lightly grease it.
Mix dry ingredients: In a bowl, whisk together flour, baking powder, cinnamon, nutmeg, and salt.
Mix wet ingredients: In another bowl, mash bananas, then stir in cottage cheese, maple syrup, eggs, and vanilla.
Combine: Slowly fold the dry ingredients into the wet, then mix in shredded carrots and walnuts (if using).
Bake for 45-55 minutes, or until a toothpick inserted in the center comes out clean. Tent with foil if the top browns too quickly.
Make the glaze: Blend Greek yogurt, powdered monkfruit, cream cheese, maple syrup, and vanilla until smooth.
Drizzle or spread glaze on cooled banana bread and enjoy!