Place all ingredients in a blender, and blend until smooth and well-combined. Place in the refrigerator to rest for at least 1 hour (this allows the bubbles formed by the blender to dissipate).
Heat a medium nonstick pan over medium to medium-high heat. Add a small amount of butter and swirl to coat the pan. Pour 1/4 cup of the crepe batter into the middle of the pan, then swirl the pan so that the batter thinly coats the bottom of the pan. Allow to cook for about 1 minute, until set and lightly browned on the bottom - small bubbles will appear on the top when it is ready to flip (just like a pancake). To flip, use a rubber spatula to gently lift the edge of the crepe. Slide the spatula under the crepe, then lift the crepe up and flip it over. Cook for about 30 seconds on the second side, then remove to a plate. Cooked crepes can be stacked on top of each other without sticking together.
Your first crepe will probably not turn out very well. This is normal; have patience, they will get better!
Make the ricotta filling:
Place ingredients in a food processor and process until combined.
Make the peach syrup:
Place the butter, brown sugar, and whiskey in a small saucepan. Bring to a boil over medium heat; add the sliced peaches and allow to simmer for 3-5 minutes or until reduced. For a thicker syrup, simmer a few minutes longer.
To assemble:
Spread 2 tablespoons of filling on half of one crepe. Fold the crepe in half, then in half again (it will now be folded into quarters). Repeat with remaining crepes. Place 1-2 filled crepes on each plate, top with the peach syrup, and dust with powdered sugar (if desired).
Notes
The honey whiskey in the peach syrup can be substituted for 1 tablespoon of orange juice plus 1/2 teaspoon of honey. The crepes and ricotta filling can be made ahead of time and stored in the fridge until assembly.