In a high-speed blender, combine milk, eggs, melted butter, flour, sugar, vanilla extract, and salt. Blend on high speed for 20 to 30 seconds until completely smooth and frothy, scraping down any flour from the sides with a spatula.

Let batter rest at room temperature for 15 to 20 minutes (or refrigerate overnight). Resting relaxes the gluten and dissipates bubbles, guaranteeing paper-thin, tear-resistant crepes.

While batter rests, melt 3 tablespoons of butter in a large skillet over medium heat. Add thinly sliced apples, brown sugar, cinnamon, nutmeg, and lemon juice.

Cook for 8 to 10 minutes, stirring occasionally, until apples are tender, translucent, and coated in a bubbling, glossy amber cinnamon syrup. Remove from heat and keep warm.

Heat an 8-inch non-stick skillet or crepe pan over medium heat. Lightly brush pan surface with melted butter.

Pour ¼ cup of batter into the center of the pan, immediately tilting and swirling the skillet in a circular motion until batter evenly coats the bottom in a paper-thin layer.

Cook for 60 to 75 seconds until the edges curl slightly and the underside is delicate golden. Carefully flip using a thin offset spatula and cook the second side for 25 to 30 seconds. Slide onto a warm plate and repeat with remaining batter.

Spoon generous portions of warm caramelized apples down the center of each crepe. Fold the sides in or fold into classic Parisian triangles.

Top with a dollop of whipped vanilla mascarpone, generously drizzle with warm salted caramel sauce, and dust with powdered sugar. Serve immediately!