Prepare the base: Preheat your oven to 375 F. Line a 9x13-inch rimmed baking sheet with parchment paper.
Add butter into a saucepot. Melt the butter over medium-high heat. Once melted, add sugar and stir until it is dissolved. Cook the butter-sugar mixture for 3 minutes, tiring occasionally. Remove from the heat and stir in salt and vanilla extract.
Pour the prepared mixture over saltine crackers. Distribute the butter-sugar mixture with an offset spatula.
Bake the crackers in the oven for 5 minutes.
Prepare the topping; chop the chocolate and set aside.
Add your almonds to a skillet and toast them over medium-high heat, for 5 minutes. Keep an eye on the almonds so they do not burn. Stir them occasionally so they are nicely toasted on all sides. Chop the almonds and set aside.
Add the chopped chocolate over the saltine crackers and bake for 45-50 seconds in the oven.
The chocolate will melt at this point. Remove the baking sheet from the oven and spread the chocolate with an offset spatula.
Add chopped almonds over the chocolate and allow the chocolate to cool down to room temperature before transferring it into the fridge.
Cool the Christmas crack for 4 hours or overnight.
Break into pieces and serve.
Notes
If you cannot find muscovado sugar, use dark brown sugar. The muscovado sugar has a rich flavor and it elevates the Christmas crack.
Almonds are just a suggestion here, but if you choose any other types of nuts, make sure to toast them. The toasted nuts have a better flavor than regular ones. Toasting nuts are more flavorful and surprisingly crunchy.
Making butter and sugar caramel can be tricky. Many experience butter and sugar separation. This will occur if you cook the caramel sauce on high heat. We suggest that you cook the caramel sauce on medium-low as stated in the recipe.