Melted chocolate chips and flaky salt make easy toppings for this sweet treat.
Line a large rimmed baking sheet with parchment paper. In a medium saucepan, stir the sugar, corn syrup, and 1/4 cup water until all of the sugar looks wet. Cook over medium heat, stirring occasionally, until the syrup comes to a simmer, about 3 minutes. Cover and cook without stirring until the mixture thickens slightly, about 3 minutes more. Stir in the butter and salt. Increase heat to medium-high and cook gently, constantly stirring, until a candy or deep-fry thermometer registers about 290°, about 5 minutes.
Off heat, immediately mix in the almonds, baking soda, and vanilla (the mixture will bubble vigorously) and quickly mix to coat. Quickly pour the mixture onto the baking sheet. Using a butter knife or metal spatula, immediately spread the brittle to a relatively even layer that’s just under 1/4 inch thick.
While the brittle is still hot, scatter the chocolate chips on top. Let sit until the chocolate melts, 1 to 2 minutes. Using the back of a spoon, spread the chocolate over the brittle in an even layer. Sprinkle with the flaky salt. Let the brittle sit uncovered until it cools to room temperature, about 3 hours.
Break the brittle into irregular bite-size pieces. Serve with ice cream or just snack on it straight. Store any leftover brittle in an airtight container in the freezer for up to 3 months.