Line a 9x13-inch baking sheet with parchment paper and sprinkle half of the chopped almonds evenly across the bottom.
In a heavy-bottomed saucepan, combine butter, sugar, water, and corn syrup. Cook over medium heat, stirring constantly until the mixture reaches 300°F on a candy thermometer (hard crack stage).
Remove from heat and quickly stir in vanilla extract. Immediately pour the hot toffee over the almonds on the prepared pan, spreading evenly with a spatula.
Sprinkle chocolate chips over the hot toffee and let sit for 2-3 minutes until softened. Spread the melted chocolate evenly across the toffee.
Sprinkle the remaining chopped almonds over the chocolate layer, pressing gently to adhere.
Refrigerate for 1 hour until completely set, then break into irregular pieces and store in an airtight container.