Have everything ready before you start. This moves quickly once the toffee is on the stove.

1. Preheat the oven to 350°F. Line a 9×13 pan or baking sheet with sides with foil and spray generously with non-stick cooking spray.
2. Arrange the pretzel thins in a single layer across the bottom of the pan. Break pieces as needed to fill the gaps. Pretzel sticks work here too if that is what you have on hand — the coverage is slightly less even but the flavor is the same.
3. In a medium saucepan over medium to medium-high heat, melt the butter, brown sugar, and salt together. Bring to a boil and cook for exactly 4½ minutes, stirring constantly. Do not walk away from the stove. Toffee burns fast.
4. Pour the toffee evenly over the pretzel layer and bake for 7–9 minutes.
5. Remove pan from the oven and immediately scatter the chocolate chips over the top. Return to the oven for 1–2 minutes, just until the chips begin to melt.
6. Spread the melted chocolate into an even layer with your offset spatula. Then scatter the chopped Cadbury eggs over the top and press them gently into the chocolate so they set — you don’t want them falling off when you break it into pieces.
7. Refrigerate until set — about an hour. Break into pieces, place bags or tins and enjoy.