How to Make It
Preheat the oven to 350°. Spread the chopped walnuts on a baking sheet and toast in the oven for 7 to 8 minutes, until browned and fragrant. Transfer to a plate to cool.
In a medium bowl, whisk together the flour and salt. Whisk in the milk, water and 2 eggs until a smooth batter forms. Set aside while you make the filling.
In a medium bowl, combine the mascarpone, ricotta, toasted walnuts, lemon zest, cinnamon and allspice. Stir in the 1/4 cup of confectioners’ sugar, 2 teaspoons of rosewater and the remaining egg until smooth. Refrigerate the filling while you make the crêpes.
In a nonstick 6-inch skillet, melt 1/2 tablespoon of the butter over moderately high heat. Pour 2 tablespoons of the batter into the skillet, immediately swirling the pan to evenly cover the bottom. Cook until set, about 45 seconds. Flip the crêpe and cook until lightly browned on the bottom, about 45 seconds more. Transfer the cooked crêpe to a work surface and repeat with the remaining butter and batter to make 11 more crêpes.
Brush a 12-by-8-inch baking dish with 1 tablespoon of the olive oil. Spoon 3 tablespoons of the filling into the center of a crêpe, fold in the sides and roll up into a tight tube. Transfer to the baking dish, seam side down. Repeat with the remaining crêpes and filling, fitting the crêpes in the baking dish snugly in a single layer. Brush with the remaining 1 tablespoon of olive oil and bake for 25 minutes, until the crêpes are light golden brown and the filling is warmed through.
Meanwhile, in a small saucepan, combine the honey and lemon juice with the remaining 1/4 teaspoon of rosewater and warm over moderate heat. Drizzle the honey mixture evenly over the crêpes, then lightly dust with confectioners’ sugar and sprinkle with the rose petals. Serve the crêpes warm or at room temperature.
Edible dried rose petals are available at specialty food shops and from amazon.com.