Chocolate and vanilla sandwich cookies

1.	For the cookies
2.	In a food processor, mix all of the ingredients, apart from the butter and egg. Add the butter and add the egg without stopping the processor. Continue beating, until the mixture comes together and forms into a ball. Separate into 4 pieces. Cover each piece of dough with plastic wrap and refrigerate for 1 hour, until firm.
3.	Preheat the oven to 190* (370*F) Fan. Line 2 baking sheets with parchment paper. With damp hands, form small balls of dough, about 2 cm in diameter. Do not make them any larger because they will spread while baking. Press down on them lightly to flatten them a bit. Place onto baking sheets, making sure to leave enough space between them. Since the dough was separated into 4 pieces, each piece of dough will fill 1 baking sheet, when molded into balls.
4.	Fill 2 baking sheets and bake for 8-9 minutes. Prepare the next batch of dough. As soon as the first batch is done, remove cookies and fill baking sheets again, and bake. In the meantime, prepare the filling.
5.	For the filling
6.	In a mixer, using the paddle attachment, cream the margarine, vanilla extract and sugar. Beat until light and fluffy. Fill a piping bag and put some filling onto the center of the cookie. Cover with another cookie. Press down lightly, so the filling can be distributed evenly.

	For the cookies
	45 g cocoa powder
	160 g all-purpose flour
	1 teaspoon(s) baking soda
	1/4 teaspoon(s) baking powder
	1 pinch salt
	250 g granulated sugar
	140 g butter, cut into cubes (frozen)
	1 egg
	For filling
	50 g margarine
	55 g butter
	240 g icing sugar
	1 level tablespoon(s) vanilla powder