In a small bowl mix together the butter powder, whole egg or yolk powder and egg white powder.
Substitution options:
1 tsp of gelatin can be replaced with 1/4 tsp of xanthan gum
Allulose can be reduced. If you eliminate it all together try increasing the oven temp to 375-400 degrees in order to get some browning on your loaf. Check for doneness before the whole 40 minutes are up.
Arrowroot can be reduced to 1 tbsp or eliminated for a lower carb count.
Butter powder can be substituted with mct oil powder for a dairy-free version.