Hi, I saw this recipe on the Food TV Network and it might be close to what you are looking for. It does not have egg whites however.

CHOCOLATE-FILLED HAZELNUT COOKIES
Source: Michael Chiarello - Food TV Network
Makes 30 filled cookies

3/4 cup hazelnuts, toasted, skins removed
1 cup confectioners' sugar
1 stick plus 1 tablespoon unsalted butter, softened
1/4 teaspoon finely grated lemon zest
1/8 teaspoon salt
1 cup cake flour
1 level tablespoon cocoa powder
3 ounces bittersweet chocolate, chopped

Preheat oven to 350 degrees F. Line 2 baking sheets with parchment paper.

Grind the nuts with confectioners’ sugar until powdery (do not make into a paste).

Blend together the butter, lemon zest, salt, and nut mixture in a large bowl with a spatula or spoon until creamy. Add the flour and cocoa powder, stirring until incorporated. Do not overwork the dough.

Roll level 1/2 teaspoons of dough into tiny balls and arrange 1-inch apart on the prepared baking sheets.

Bake 1 sheet at a time until lightly crisped, about 12 minutes. Slide the parchment paper with the baked cookies onto a rack to cool.

In a microwave-safe bowl, melt the chocolate in the microwave.

Spoon a mound, about 1/8 teaspoon, of melted chocolate onto the flat side of a cookie then top with the flat side of another cookie to make a "sandwich". Repeat.

Plain cookies can be baked and cooled 1 week ahead and kept at room temperature in an airtight container. Fill when ready to serve.