This recipe makes about 20-22 Sylvana cookie sandwiches.
You’ll need your hand or stand mixer with the whisk attachment, a bowl (if you’re using a hand mixer), a rubber spatula, an offset spatula, a grinder or any sort of food processor, measuring cups and spoons, a couple of baking sheets, parchment paper, and a Sharpie (a marker) - or you can use a baking mat with pre-set measurements on it (I did).
6 egg whites, room temperature
1/2 tsp cream of tartar
3/4 cup granulated sugar
1 1/2 cup ground, unsalted cashews
1 cup (2 sticks) butter, room temperature
3/4 cup icing sugar, sifted
2 tablespoons milk
1/2 tsp vanilla extract
1 cup finely ground shortbread biscuits or cake crumbs (you can even use Mamon Tostado or lady fingers)
1. Preheat the oven to 300F. Cut up some parchment paper to line the baking sheets and set aside, around 4-5 pieces. Make another master template drawing some round or oval shapes with a Sharpie (like you would space out cookies in a sheet), about 2 inches apart. You can just put the master template under the plain sheets so you don’t bake WITH the marker scent. (I have an oven mat with circles and measurements already marked on it so I just used this instead of making a master template.)
2. With a whisk attachment using your hand or stand mixer, beat egg whites at medium speed until frothy and almost to soft peaks. Add the cream of tartar and continue beating until soft peaks form. Gradually add the sugar and start beating and increase the speed to until they form shiny stiff peaks. When you take out the whisk, it should be able to hold its form.
3. Fold in the ground cashews in 2-3 parts. Make sure not to over-fold so you don’t deflate the meringue.
4. Using a spatula, transfer the mixture to a piping bag with a plain round tip (if you don’t have one, that’s okay. You can always level or smoothen out the piped mixture with an offset spatula.) Take the template you used and place it under the parchment paper. Place a plain cut-out parchment sheet on top and place both on a baking sheet (I crumpled mine so it doesn't slide around). Pipe the meringue onto a cookie sheet lined with parchment. (For easier transfer, place the piping bag inside a tumbler or large glass and start filling it.)
5. Bake them and place on the middle rack for 30-35 mins or until lightly browned. If you need to swap out the trays, do it halfway through the time.
6. While the wafers are baking and cooling, we can prepare the buttercream. Using your mixer (hand or stand), use the whisk attachment again and beat the butter and the powdered sugar together for a few minutes at high speed, add the vanilla as well. You want a light, airy, and frothy buttercream. Exactly like whipped butter.
7. Once the wafers are done, cool them completely before detaching from the parchment paper. You could easily remove them if they are cooked through.
8. Avengers, assemble! (Wife-of-a-fan mode) Yup - assembly time. Holding one wafer with the flat side-out, spread some buttercream on a cookie and sandwich it with another cookie. Sandwich them and press. Spread some buttercream on the sides and roll the sandwich in biscuit crumbs coating all the sides. Spread some buttercream again on the top cookie, spread and top with biscuit crumbs and do the same for the bottom cookie.
9. Place the Sylvanas in the freezer - and you can leave them there for storage. You can actually eat them straight from the freezer because you made whipped buttercream, it won’t be tough to eat. But if you prefer, you can also transfer to the chiller for some minutes before serving.