Preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper or silicone baking mats.

In a large bowl, beat the softened butter, granulated sugar, and brown sugar together with an electric mixer on medium speed until light and fluffy, about 3 minutes. Scrape down the sides as needed.

Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract until combined.

In a separate medium bowl, whisk together the flour, baking soda, and salt. Gradually add the dry mixture to the wet mixture, mixing on low speed just until no streaks of flour remain. Do not overmix.

Gently fold the toffee bits into the dough with a rubber spatula until evenly distributed.

Cover the bowl with plastic wrap and refrigerate the dough for at least 30 minutes (or up to 2 days). Chilling solidifies the butter, which helps create the crinkly crackly tops.

Place the 1/4 cup granulated sugar for rolling in a shallow bowl. Scoop rounded tablespoons of dough (about 1.5 inches in diameter) and roll into balls. Roll each ball in the sugar to coat completely, then place on the prepared baking sheets about 2 inches apart.

Bake for 10-12 minutes, or until the edges are set and lightly golden, and the tops are crinkled and crackly. The centers will still look slightly soft.

Immediately after removing from the oven, sprinkle a pinch of flaky sea salt over each cookie. Let the cookies cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.