Why is my toffee grainy?
Graininess usually comes from sugar that did not fully dissolve or from sugar crystals forming on the sides of the pan and sneaking back into the mix. Melt the butter, add the sugar, and whisk until it looks totally smooth before it boils. Once it hits a real boil, keep stirring gently and constantly for the full 3 minutes. If you see sugar stuck on the sides, carefully wipe down the sides with a damp pastry brush (or just avoid scraping the sides into the toffee).
Why did my toffee separate and look oily?
That is the butter breaking from the sugar. It can happen if the heat is too high or the boil is uneven. Use medium heat, whisk steadily, and make sure you actually hit a full bubbling boil (bubbles across the surface, not just around the edges) before starting your 3 minute timer. If it starts separating, pull it off the heat and whisk like you mean it. It is usually salvageable. Then pour immediately.
Do I have to use saltines?
No. Matzo, club crackers, or even butter crackers work. Saltines are the classic because they are thin, sturdy, and salty, which keeps the sweetness balanced.
What chocolate works best?
Semisweet chips are the safest. Milk chocolate is sweeter and softer. Dark chocolate is more grown up and extra balanced. You can also do a mix.
Can I add nuts or other toppings?
Absolutely. Toasted pecans, walnuts, or sliced almonds are great. Add them after you spread the melted chocolate, then press gently so they stick.