Step 1

In a blender, combine the milk, water, eggs, melted butter, sugar, orange zest, and salt. Blend until well combined, about 15 seconds. With the blender running on medium speed, gradually add the flour until combined, about 15 seconds more. Let the batter sit at room temperature, until slightly bubbly, about 20 minutes. Continue with the sauce while the batter rests.

Step 2

In a large skillet, bring the orange zest, orange juice, butter, and sugar to a boil over medium-high heat, stirring occasionally. Reduce the heat to medium-low, and stir in orange liqueur. Simmer, stirring occasionally, until syrupy, about 15 minutes. Reduce the heat enough to just keep the sauce warm.

Step 3

Brush a crepe pan or small skillet with melted butter; heat over medium-low heat. Add about 1/4 cup batter, swirling into an even layer. Cook, undisturbed, until light golden brown, about 1 to 2 minutes. Carefully flip the crepe and continue cooking until light golden brown, about 30 seconds more. Remove from the skillet. Gently fold into quarters and place on a tray or plate. Repeat with the remaining batter, brushing the pan lightly with melted butter in between each crepe.

Step 4

Once cooked, add all of the folded crepes to orange sauce. Cook over medium-low heat, undisturbed, until warmed through, about 3 minutes. Serve immediately, spooning additional sauce over crepes. Serve with vanilla ice cream, if desired.