Preheat oven to 350 degrees F. Line a large baking sheet with a Silpat baking mat or parchment paper and set aside.
In a medium bowl, whisk together flour, baking powder, baking soda, and sea salt. Set aside.
Using a stand mixer, cream butter, sugars, and espresso powder together for about 1 minute. Add in the eggs and vanilla and mix until combined. Add the dry ingredients. Mix on low until just combined. Don't over mix. Use a spatula to stir in the chocolate chunks and toffee bits.
Form the cookie dough into balls, about 2 tablespoons of dough. Place on prepared baking sheet, about 2 inches apart.
Bake cookies for 10-12 minutes or until the edges are slightly golden brown. Remove from oven and sprinkle with flaky sea salt. Let the cookies cool on the baking sheet for 2-3 minutes. Transfer to a wire cooling rack and cool completely.
The cookies will keep in an airtight container for 3-4 days. You can also freeze the baked cookies or cookie dough balls for up to 3 months.