Preheat the oven to 350 degree F. Put the almonds on a baking sheet and roast for 12-14 minutes, stirring once in the middle to ensure they brown evenly. When the almonds are golden brown and fragrant, remove the pan from the oven and allow the almonds to cool.

When the nuts are cool, put them in a food processor and pulse until chopped into 1/8-inch pieces. You can also do this with a knife.

Line a 9x9 baking pan with parchment paper.

Add the butter, water, corn syrup, and salt to a heavy bottomed pot over medium heat and melt the butter, stirring to keep the mixture emulsified.

Add the sugar into a mound in the center, being very careful not to get any sugar crystals on the sides of the pot. Cover with a lid and cook without stirring until the sugar is dissolved.

Remove the lid, turn down the heat to medium low and cook, stirring continuously until the toffee reaches 300 degrees F.

Remove the pot from the heat and stir in the vanilla and half of the almonds.

Pour the butter toffee onto your lined baking sheet and spread into a 1/4-inch thick sheet. Be very careful as the toffee is a hot and sticky!

Distribute the chocolate over the top of the toffee in a roughly evenly layer and let it melt.

When the chocolate has melted, spread it into an even layer on top of the toffee.