Preheat the oven to 300F and line 2 baking trays with parchment paper.
Whip the whites and meringue powder until they are foamy, then slowly add the sugar and whip just until the whites barely hold a soft peak when the beaters are lifted. It is very important not to overwhip your egg whites). Stir the ground almonds and icing sugar together and then fold this into the whipped whites in 2 additions (the batter will be quite runny).
If you wish to colour the macarons, divide the batter into 3 bowls and stir in a touch of colour into each. Fill 3 piping bags fitted with a plain tip with each of the batters and pipe macarons that are 1 ½ -inches wide and an inch apart on the baking tray. Let the macarons sit for 10-30 minutes, until they develop a “skin” (until the surface of the macarons appear dull – no longer shiny). Bake for about 10 minutes, until they lift off the parchment paper using a spatula without sticking. Let them cool on the trays before removing.
To assemble, pipe or spread a little curd or marmalade on the bottom of one macaron and press the bottom of a second onto it, pressing gently. Continue until all of the macarons are filled. Repeat steps 1 through 4, to make enough macarons to achieve a tower of 80 to 100 macarons.
Beat the icing sugar, meringue powder and 2 tbsp of the water until a smooth but structured icing, adding more water if needed. Divide the icing into 3 bowls and tint it to match the 3 colours of the macarons. Keep the icing covered with plastic directly on the surface until ready to use.
Place the Styrofoam cone on your desired platter and cover with the paper, adhering with royal icing.
Fill 3 small parchment cones or piping bags with each of the royal icings and, starting at the bottom, pipe a little royal on once side of a macaron and stick it to the paper. Build a bottom layer with one colour of macaron and then build a second tier with another colour and continue building up to the top of the cone. Place a final macaron upright on the very top and let the tower set for at least 2 hours before moving.
Makes 80-100 macarons