• Line a 13×9 baking pan with parchment paper and lightly butter it. Preheat oven to 350 degrees.
• In the bowl of a stand mixer or in a large bowl with a hand mixer, beat together butter and sugar until it’s light and fluffy, 2-3 minutes. Add peanut butter and beat until combined. Beat the eggs and egg yolk and vanilla into the mixture.
• With the mixer on low speed, add in flour until it's just combined, taking care not to over-mix. Fold in the chocolate chips.
• Spread the batter into the prepared pan making sure to smooth the top. Bake for 40-45, until it's golden on top and a toothpick stuck in comes out clean. Let blondies cool completely.
• Spread the ganache on the blondies and let stand for about 15 minutes to harden. Lift blondies out of pan with parchment paper and slice into squares and serve.

Chocolate Ganache

• Place chocolate chips in a medium heatproof bowl. Add cream to a small saucepan and bring just to a boil. Pour cream over the chocolate chips and let it stand for a minute to melt chocolate a bit.
• Whisk in the butter and keep whisking until the chocolate is fully melted and smooth.