Preheat oven to 350°F. Line a large baking sheet with aluminum foil or parchment paper then, spray with non-stick spray.
Line up your saltine crackers in a single layer in rows on the tray. It may be necessary to cut some crackers to fill in smaller gaps.
Grab your saucepan and heat your butter in low heat. As you add your sugar, increase your heat to medium and stir until sugar dissolves. Boil with constant stirring for four minutes until color turns to caramel. Remove from heat and add in the espresso powder.
Pour the mixture over the crackers and evenly spread it using an offset spatula.
Bake for four to five minutes until the top begins to form bubbles. Take out from the oven and add the semi-chocolate chips. Put back for about two minutes until chocolate chips melt.
After you have removed it out from the oven, spread the melted chocolate over the top with a clean spatula.
Add the peanut butter chips to the chocolate for two minutes until it melts. Swirl the melted peanut butter chips to the chocolate using the pointed end of the fork.
Cool to room temperature, about thirty minutes. Then cover with foil and refrigerate until set or freeze for fifteen minutes until chilled.
Transfer the toffee to a cutting board using the foil overhang. Peel off the foil off the back of the crackers and cut into squares. Serve and enjoy!