Preheat the oven to 350 degrees F. Line a 9x5 loaf pan with parchment paper and grease.

Mix the brown sugar and butter in the bowl of your stand mixer over medium speed until light and fluffy. Add the baking soda, 1/8 teas salt, and the egg white and mix. Scrape down sides if needed. Stir in the oats and 3/4 cup flour, mix until just combined.

Scoop out 1/4 of the oat mixture, and press the rest of the mix into the prepared loaf pan.

Bake the oat bar layer for 12 minutes, until just set.

In a clean bowl, whisk together the remaining whole egg, sugar, canola oil, 1/8 teas salt, cocoa powder, baking powder, and the 1/4 cup flour. When combined, fold in the semisweet chips.

Pour the chocolate mix over the oat bars.

Stir the walnuts and remaining 1 tbs oats into the reserved oat bar mixture and crumble over the top of the cocoa layer. Bake for 10 to 12 minutes, being careful not to over bake or the bars will become dry.