📖 Instructions

1. Preheat your oven to 350°F (175°C). Line a 9x13 inch baking pan with parchment paper, leaving an overhang on the sides. This makes lifting the bars out later much easier – trust me, you'll thank yourself later!
2. In a large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy. I like to use an electric mixer for this, but a good old-fashioned wooden spoon works too. Just put a little elbow grease into it!
3. Beat in the eggs one at a time, then stir in the vanilla extract. Make sure everything is well combined; nobody wants a clump of unmixed egg in their bar.
4. In a separate bowl, whisk together the all-purpose flour, cocoa powder, baking powder, and salt. This ensures that the dry ingredients are evenly distributed.
5. Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Be careful not to overmix; overmixing can lead to tough bars. We want them to be tender and melt-in-your-mouth.
6. Stir in the chopped hazelnuts. These add a delightful crunch and nutty flavor that complements the chocolate perfectly. If you're feeling fancy, you could even toast the hazelnuts beforehand for an even deeper flavor.
7. Pour the batter into the prepared baking pan and spread it evenly. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out with moist crumbs. Keep an eye on them; ovens can be finicky!
8. Let the bars cool completely in the pan before frosting. This is crucial; if you frost them while they're still warm, the ganache will melt and make a mess.
9. While the bars are cooling, prepare the chocolate ganache. In a saucepan, heat the heavy cream over medium heat until it just begins to simmer. Watch carefully, as you don't want it to boil over.
10. Remove the saucepan from the heat and add the chopped semi-sweet chocolate. Let it sit for a minute to soften, then whisk until smooth and glossy. If the chocolate isn't melting properly, you can return the saucepan to low heat and stir until smooth.
11. Stir in the hazelnut spread until well combined. This adds an extra layer of hazelnut flavor and makes the ganache incredibly rich and decadent.
12. Pour the ganache over the cooled bars and spread it evenly. Sprinkle with additional chopped hazelnuts, if desired. I always add extra; you can never have too many hazelnuts!
13. Refrigerate the bars for at least 30 minutes to allow the ganache to set. This makes them easier to cut and serve.
14. Once the ganache has set, lift the bars out of the pan using the parchment paper overhang. Cut into squares and serve. Enjoy every heavenly bite!