Butter a 9 x 13 x 2-inch baking pan and set aside.

Place the sliced almonds in the bowl of a food processor fitted with the metal blade. Pulse until the almonds form a fine powder. Transfer the almond powder to a small bowl and set aside.

In the same food processor, pulse the toasted pecans for 1 to 2 seconds, or until they are coarsely chopped but not powdered. Set aside.

In a medium saucepan over low heat, melt the butter. Once the butter is about halfway melted, add the sugar and water. Cook over low heat, stirring very gently, until the mixture is fully combined.

Attach a candy thermometer to the side of the saucepan. Increase the heat to medium-high and cook until the mixture reaches 300°F, about 15 minutes. The mixture will bubble and turn golden brown. If the browning appears uneven, gently swirl the pan during cooking, but do not stir.

While the toffee is cooking, place the dark chocolate and milk chocolate together in a medium bowl.

Once the toffee reaches 300°F, remove the saucepan from the heat and remove the candy thermometer. Stir in the chopped pecans.

Pour the hot toffee mixture into the prepared pan and allow it to spread evenly.

Let the toffee rest for 1 minute. Sprinkle the chopped dark and milk chocolate evenly over the surface. Let the chocolate sit for about 3 minutes to melt, then use an offset spatula to spread it into an even layer.

Sprinkle the almond powder evenly over the melted chocolate.

Place the pan in the freezer for about 30 minutes, or until fully set.

Remove the pan from the freezer and use a sharp knife to break the toffee into pieces.