Preheat oven to 350°F (175°C). Line a 9x13-inch baking pan with aluminum foil and arrange saltine crackers in a single layer, salted side down.
In a medium saucepan, melt butter over medium heat. Stir in brown sugar, 1 teaspoon cinnamon, and vanilla. Bring to a boil, stirring constantly, and boil for 3 minutes until thickened.
Pour the hot sugar mixture evenly over the saltine crackers, spreading gently with a spatula to cover completely.
Bake for 10–12 minutes, or until bubbly and golden. Remove from oven and immediately sprinkle chocolate chips over the top. Let sit for 2–3 minutes until melted, then spread evenly.
In a small bowl, mix granulated sugar and 1/2 teaspoon cinnamon. Sprinkle evenly over the melted chocolate.
Allow to cool completely at room temperature, then refrigerate for 30 minutes to set. Break into pieces and serve.
Notes
Store in an airtight container at room temperature for up to 1 week, or refrigerate for longer freshness.