In a large bowl, combine the flour, protein powder, baking powder, and salt.
Make a well in the middle by pushing the dry ingredients to the sides and pour in the milk, eggs, butter, and vanilla (if using). Break up the eggs with a fork first, then incorporate them into the other liquid ingredients. Mix the batter, working the dry ingredients from the outside-of-the-bowl-in, until there are no visible lumps.
Add the blueberries to the bowl and, using a spatula, gently fold them in with a couple of turns. The batter is thick but pourable. See the recipe notes when using a plant-based protein.
Cook the pancakes:
Heat a large non-stick pan (or griddle) over medium-high heat. Once hot, grease the surface with butter, oil, or spray. Immediately, scoop ¼ cup of pancake batter onto the greased surface, making sure you pick up an even amount of blueberries in each scoop.
Cook the first side for about 2 minutes, until the edges begin to look defined and bubbles form. Flip the blueberry pancakes over and cook for another two minutes. Avoid pressing down with a spatula. Remove the pancakes from the pan onto a plate. Repeat the process with the remaining pancake batter. Rinse the pan between batches if your pancakes are burning quickly, but the middles are not yet cooked (and reduce the heat).
Serve and store:
Serve them immediately or keep them warm. Then, stack them up, and top them with your favorite toppings and syrup.
Store leftover cooked and cooled pancakes in an airtight container in the fridge for up to 4 days, or freeze flat for up to 3 months. Warm them up in the microwave or toaster.
Notes
Vanilla and unflavored protein powder work best when making pancake batter.
Plant-based proteins work, but you'll often need to add about 2 to 3 tablespoons of additional liquid to thin out the batter, but no more than ¼ cup, or the batter will be runny.