Line an 8 x 8 inch loaf pan or cake tin with parchment paper and set aside.
In a mixing bowl, add the oat flour and vanilla protein powder and set aside.
In a microwave-safe bowl or on the stovetop, combine the peanut butter with brown rice syrup and melt together. Whisk to ensure it is combined. Pour into the dry mixture and mix until fully incorporated. If the batter is a little crumbly, slowly add water until it is smooth.
Pour the batter to a lined baking dish and press firmly into place. Refrigerate for at least 20 minutes to firm up.
While the bars are firming up, melt the chocolate with coconut oil and drizzle over the top. Let it set before slicing.
Notes
Protein powder: Any protein powder works, including non-vanilla flavored ones. I recommend Optimum casein vanilla and Growing Naturals vanilla.
Liquid: I use water, but feel free to use milk.
Leftovers: Keep in the fridge for up to 3 weeks or the freezer for 3 months.