Use butter to grease a 7 x 11-inch pan, or 9 x 12-inch for slightly thinner Roca.
Sprinkle 1 cup of toasted almonds on bottom of the pan.
In a heavy saucepan, at medium-high heat, melt butter and add brown sugar.
Stir until gently boiling.
Reduce heat to medium, or medium-low, and boil 12 minutes exactly, stirring constantly.
Remove the mixture from heat, give it a good stir to mix up that butter and sugar one more time, and immediately pour the hot mixture into the pan over the almonds.
Place the chocolate bars on top.
Let them sit a minute or so until melted, then spread chocolate around carefully.
Sprinkle with the remaining toasted almonds, and gently press them into the chocolate.
Cool completely and then break apart into chunks with a sharp knife.
Store in a covered container.