Preheat oven to 350℉.
Line a baking sheet with parchment paper or a silicon baking mat.
Spread hazelnuts evenly across pan and toast in oven for 10 minutes. Keep a close eye on the nuts as they go from nicely roasted to burnt if left unattended.
Once the hazelnuts are toasted remove the pan from oven and set aside to cool.
Grind the cooled nuts in food processor until you have a course even texture. Put the nuts to the side for now and get started on your banana bread batter
In a small bowl combine flour, salt, and baking soda. Whisk togther.
In a large bowl cream sugar and butter together with a mixer set to medium speed. Add in banana, egg, Greek yogurt. Mix with electric beater until blended.
Add in flour mixture and mix until fully incorporated.
Spoon 1/4 banana bread batter into separate bowl and set aside.
Place chocolate chips in small bowl and melt in microwave for 1 to 2 minutes, depending on your microwave. Heat until just melted and soft.
Add ground hazelnuts to melted chocolate and mix in. Add the chocolate hazelnut mixture to the 1/4 batter and stir in.
Grease a 8 ½ x 4 ½ inch loaf pan. Lay half banana batter onto bottom of pan. Using a spoon alternate drops of chocolate hazelnut mixture and plain batter on top of bottom layer. When all of chocolate batter is used up, layer the remaining plain batter over top.
Using a for drag the batter slowly and with a swirling motion to create your "chocolate swirl" pattern.
Bake banana bread loaf for 1 hour and 15 minutes or until a knife comes out clean. Let the banana bread cool, before finishing with the peanut butter caramel sauce.