Preheat the oven to 180c. Beat the butter, sugar, vanilla and eggs together in a large mixing bowl until smooth then sift in the flour, cocoa and baking powder. Thoroughly grease the moulds of a 6-hole muffin tin and evenly divide the batter into each. Bake for 18 minutes, or until set around the edges and risen - but still slightly underdone.
Meanwhile, grease the underside of a second muffin tin with butter or oil, around the bottom and sides of the outside of each mould. As soon as you take the brownies from the oven, press the other muffin tin firmly down on to the brownies, flattening the centres of the cakes and causing their edges to splay up. After holding the tin in place for a few seconds, slowly remove it to reveal the bowl-shaped brownies. Leave to cool completely before removing from the tin.
Make the handles: Measure the diameter across the top of the baskets, as this is the size you will need to make your handles. Draw 6 semicircles onto a piece of greaseproof paper with the size handle you want and that will fit your baskets. Keep them all uniform and as even as possible. Melt half of the chocolate in a small bowl in the microwave, on a low heat and stirring every 10 seconds. You don’t want the chocolate to get hot, only warm enough to melt. Spoon into a piping bag. Once it is just the right temperature- still warm enough to pipe but not so cold it has set- snip the end of the piping bag. Pipe along your handle traces, staying as neat as possible. You can layer up the chocolate, giving the handle a rustic, weaved appearance. Leave to one side to set for 5 minutes.
Decoration
Melt the remaining 100g of chocolate and pour into each basket. Roll the chocolate around each basket to coat the inside and create a lining of chocolate. Leave to cool and harden for a couple of minutes. If desired, roll out the fondant icing to a depth of 2mm. Using a cookie cutter, cut out 6 rounds that are the right size to line the inside of the baskets. Attach the now set chocolate handles to the baskets by securing with a few more drops of the melted chocolate. This will set and secure them in place. Using some more fondant icing, roll out 6 long thin sausage shapes, fold each in half and twist them together to create a coloured twine. Use this to decorate the rim of each basket and secure the ends with a little cold water to help them stick together. Fill each basket with a few Easter eggs and serve.
