Preheat the oven to 350°F (177°C). Spray a 24-count mini muffin pan with nonstick cooking spray and set aside.
In a large mixing bowl, mix together the melted butter and granulated sugar. Add in the eggs and vanilla extract and mix until well combined. Sift in the flour, cocoa powder, and salt and mix until just combined.
Evenly distribute the brownie batter between all 24 mini muffin cavities. Bake at 350°F for 12 to 15 minutes or until a toothpick inserted into the brownies comes out clean with just a few moist crumbs. Remove from the oven and gently press in the center of each brownie with the bottom of a measuring teaspoon. Transfer the pan to a wire rack and allow to cool in the pan for at least 45 minutes.
Remove the cooled brownie bites from the pan and place them back onto the wire rack.
To make the caramel filling:
Add the soft caramel candies and heavy cream to a large microwave safe bowl. Microwave in 20 to 30 seconds increments, making sure to stir well after each increment, until completely melted and smooth. Evenly distribute the caramel between all 24 brownie bites (about 1 teaspoon per each brownie bite).
Allow to cool for at least 15 to 20 minutes so the caramel can firm up, then top with sea salt as desired.
Store leftover brownie bites in an airtight container at room temperature for up to 4 days.To prepare ahead of time: You can bake the brownie bites 1 to 2 days in advance. I recommend storing them in an airtight container at room temperature. On the day you plan on serving them, make the caramel filling and fill the brownie bites. Freezing Instructions: Brownie bites will freeze well in a freezer bag or container for up to 3 months. Thaw to room temperature, and fill with the caramel the day that you plan to serve them.Butter: I recommend using unsalted butter in this recipe so that you can control the amount of salt. If using salted butter, reduce the salt in the brownie batter from 1/4 teaspoon to a tiny pinch.Caramels: It's best to stick with a soft caramel candy for the filling, I really love Kraft's soft caramels.Heavy Cream: You may also substitute milk for the heavy cream in the caramel filling.