Ingredients
12 full-size graham cracker squares (about 1 standard sleeve), kept dry and whole
1/2 cup (1 stick) unsalted butter
3/4 cup packed light brown sugar
1 cup semisweet chocolate chips
Directions
Prepare the slow cooker: Lightly coat the inside of a 4- to 6-quart slow cooker with nonstick cooking spray or a very thin film of butter. This helps keep the graham crackers and melted chocolate from sticking and makes cleanup easier.
Arrange the dry graham cracker squares: Lay the dry graham cracker squares in a single, even layer on the bottom of the slow cooker. Break a few crackers as needed so they fit snugly and cover as much of the bottom surface as possible, as shown in the process shot where the dry squares are neatly arranged.
Make the simple caramel mixture: In a small saucepan over medium heat, melt the butter. Stir in the brown sugar and cook, stirring constantly, until the mixture is smooth, bubbling around the edges, and looks like a glossy caramel, 2 to 3 minutes. You do not need to boil it hard; you just want the sugar mostly dissolved and the mixture well combined.
Pour caramel over the graham crackers: Immediately and carefully pour the hot butter–brown sugar mixture evenly over the layer of dry graham crackers in the slow cooker. Use a heatproof spatula to gently nudge the mixture so most of the crackers are coated. Some dry spots are fine; the caramel will spread more as it cooks.
Slow cook until bubbling: Cover the slow cooker with the lid. Cook on LOW for 1 1/2 to 2 hours, or until the caramel is bubbling around the edges and the graham crackers have softened slightly but still hold their shape when gently pressed with the back of a spoon. Avoid lifting the lid too often, as that releases heat and can slow the process.
Add chocolate chips: Turn off the slow cooker. Immediately sprinkle the chocolate chips evenly over the hot caramel-coated graham crackers. Cover the slow cooker again and let sit, with the heat off, for 5 to 10 minutes so the chocolate chips melt from the residual heat.
Spread and cool slightly: Once the chocolate chips are glossy and soft, use a spatula to gently spread the melted chocolate into an even layer over the graham cracker base. Let the dessert cool in the uncovered slow cooker for at least 20 to 30 minutes to firm up slightly before serving. For cleaner slices, cool longer until just warm or room temperature.
Serve: Scoop the dessert out with a spoon for a rustic, gooey presentation, or run a thin spatula around the edges and cut into squares or rectangles directly in the slow cooker. Serve warm or at room temperature. Store any leftovers, once fully cooled, in an airtight container at room temperature for up to 2 days.
Variations & Tips
For a nutty twist, sprinkle 1/2 cup of chopped pecans or walnuts over the hot caramel layer before cooking, then proceed with the chocolate chips as written; this adds crunch and makes the dessert taste like a slow cooker version of toffee bars. If you prefer a sweeter, milkier chocolate flavor, swap the semisweet chocolate chips for milk chocolate chips or a mix of both.