Preheat the oven to 400 degrees.

Line a rimmed baking sheet with aluminum foil up around edges.

Arrange the matzo crackers in a single layer on the foil, breaking them as necessary to fit.

Melt the butter in a medium saucepan over medium-high heat. Stir in the sugar and kosher salt and bring to a boil. (the mixture should be bubbling all over, not just on the edges) Continue to boil for 2 to 3 minutes, stirring occasionally. Remove from the heat and stir in the vanilla.

Pour the mixture over the top of the matzo. Using a rubber spatula, quickly spread the toffee mixture to coat the matzo. Bake in oven until the toffee is bubbling, about 5 to 6 minutes.

Take out of oven and sprinkle the chocolate chips over the hot toffee in an even layer. Let sit until the chocolate is melted, about 5 minutes. Use a spatula to gently spread out the chocolate, then sprinkle with the sea salt, if using. Let sit at room temperature for 1 hour, then refrigerate for another hour to set completely.

Break into pieces and serve, or store in an airtight container at cool room temperature for up to 2 weeks.