Trim the edges of 6 of the Dobos layers to make them 8 in/20 cm in diameter. Place one layer on an 8-in/20-cm cardboard cake round. Moisten with simple syrup and, reserving 8 oz/230 g of the buttercream for décor, apply a thin, even layer of buttercream. Top with a second Dobos layer, moisten with syrup, and spread with buttercream. Repeat the process with the remaining