Preheat oven to 180 Cº (350 Fº).
Add rolled oats, pumpkin seeds, flaxseeds, protein powder, sea salt and baking powder to a high speed blender. Pour in milk of choice and process until smooth - the oats should have now become flour.
After blending, let protein oat cracker batter rest for five minutes.
Line a 20 x 30 cm (9 x 13 inches) baking pan with parchment paper. Spread over the pan protein crackers dough as thin as possible. Try to evenly spread batter, so that the oat crackers can bake uniformly. If desired, sprinkle top with pumpkin seeds.
Bake for 10 minutes, then remove pan from the oven and cut crackers sheet into small squares.
After cutting, bake protein crackers for additional 18 to 25 minutes, or until golden and crispy. But do not over-bake, they will get crispier while cooling.
Allow oil-free protein crackers to cool before serving.