Cream the butter and sugars until light and fluffy. Add the vanilla and salt and mix. Add the eggs and beat until smooth.
Add the flour, baking powder, baking soda, and cornmeal and beat until just mixed, scraping down the bowl as you go. Add the chocolate chips and toffee bits and beat until just combined.
Drop the batter by spoonfuls (I used a tablespoon cookie scoop) onto a parchment-lined baking sheet. Leave at least 2 inches between the cookies as they will spread a bit.
Sprinkle the top of each cookie with flaky sea salt (I like Maldon), and bake for 10-15 minutes or until golden brown on the edges. Let cool on the sheet until firm enough to transfer to a cooling rack.