Preheat the oven to 425 degrees F.
Line 1 large sheet pan with aluminum foil and spray with nonstick oil. Arrange the saltine crackers salt-side up in a single layer; set aside.
In a medium saucepan, add butter and brown sugar, and stir over medium heat. Let it come to a boil and simmer until it turns a caramel color. This only takes a few minutes. Immediately remove from the heat and slowly pour the caramel over the crackers. Make sure to evenly coat the crackers. Place the pan in the oven and bake for 4-5 minutes, or until the caramel starts to get all bubbly.
While it is cooking, add chocolate chunks to a microwave safe bowl and heat for 1 minute. Stir and heat again for 1 minute until mixture is melted and smooth. Set aside.
Once it is bubbly, remove the pan from the oven. Slowly pour the chocolate mixture evenly over the caramel saltines. Once you pour all the chocolate, make sure to evenly spread it with a butter knife.
Immediately sprinkle the “candied” pecans over the chocolate mixtures, make sure to scatter them evenly over the pan.
Transfer the pan to the freezer for 20 minutes, or until completely hard and cold. Once they are chilled, break up into pieces like pictured. Store in an airtight container. We prefer to store them in the fridge, but they will be fine at room temp.