In a large bowl, sift together the oat flour, whole wheat flour, baking powder, and salt.
In another bowl, whisk the eggs and sugar together. Stir in the milk.
Make a well in the flour mixture and gradually pour in the egg and milk mixture whisking continuously. Gradually whisk in the olive oil and hot water until smooth.
Heat a crepe pan or skillet over medium heat. Brush with some butter or ghee.
Add about 1/3 cup of the batter and tilt the skillet to distribute the batter evenly. Cook for about 1 minute, until the edges curl up and start to brown. Flip the crepe and cook for about 30 seconds more until set. Transfer to a large plate and repeat with the remaining batter, making sure to butter the pan between each crepe.
Make the filling by beating the ricotta, vanilla extract, lime zest, and maple syrup together in a bowl using a hand mixer.
Spread the filling over the bottom half of a crepe, layer some diced mango on top of it, and fold into quarters. Top with more diced mango and chopped pistachios.