Preheat oven to 350F and line cookie sheet with parchment paper.
In a medium-sized saucepan, combine butter, sugars, and corn syrup.
Cook over medium heat, stirring contantly, until sugar has melted and mixture just begins to boil.
Once boiling, remove from heat and stir in vanilla extract, salt, flour, and finely chopped almonds, stirring until completely combined.
Allow to cool for five minutes, then drop by 1 ½ teaspoon onto prepared cookie sheet, spacing cookies at least several inches apart (cookies will spread quite a bit in the oven, so give them some space!).
Bake on 350F for 9 minutes, rotating halfway through baking. You can usually tell the cookies are finished baking when they stop bubbling and are a light golden brown in color. Keep an eye on them because they can burn quickly.
Allow cookies to cool completely on baking sheet. They won't be crisp until cooled.
Keep in mind that the lace cookie batter/dough will thicken as it cools, that is completely fine and won’t affect the outcome of the cookies.
¹I usually will measure out the almonds and then pulse in a food processor until finely chopped.
I've successfully made these lace cookies nut-free by substituting ⅔ cup of whole oats (I do not put them in the food processor) for the almonds.