Line an 8x10 baking sheet with a silicone baking mat.Melt butter in a saucepan over medium heat.
Add sugar, 2 tablespoons water, and salt. Stir occasionally until it comes to a boil.Continue cooking without stirring until the mixture reaches 290 degrees F.
Remove from heat and add in vanilla and 1 cup almonds.
Spread out mixture on the baking sheet.
Let set for about 45 minutes, until mixture is set but still pliable. Score into rectangles.Break sheet of toffee into individual pieces.Melt and temper chocolate. (If you don't want to temper the chocolate, you don't have to, but the resulting candy will be softer and should be refrigerated).
Place remaining 2 cups chopped almonds in a large bowl. Line a baking sheet with parchment or wax paper.Dip toffee pieces in chocolate and then roll in chopped almonds.
Place on baking sheet and let set before eating or wrapping.