Preheat oven to 350 and line a baking sheet with parchment paper.

Spread walnuts in an even layer on sheet pan, and bake 5-7 minutes, until lightly toasted and fragrant. Toss occasionally. Remove pan from oven and let cool.

Spray a 9" x 13" metal baking pan with nonstick spray, and line with parchment paper, leaving an overhang on the short sides of the pan. Set aside.

In a medium bowl sift together flour, baking powder, and salt, then set aside.

Melt butter in a medium sauce pan over medium heat, stirring frequently. Cook until light brown bits form on bottom of pan, about 8 minutes. Remove from heat.

In a stand mixer fit with the paddle attachment, add brown sugar and browned butter. Mix on medium until combined, about 2 minutes.

Add eggs and vanilla, and mix until light and fluffy, another 2 minutes.

Add flour mixture, and beat until combined and a thick dough forms.

Pour batter into parchment lined pan, and smooth into an even layer using a butter knife or offset spatula. Bake shortbread until golden brown, edges crisp and separate from pan, and a toothpick comes out mostly clean, 20-25 minutes.

Transfer pan to a rack and cool for 15 minutes, then transfer to the freezer for another 15 minutes. Crust should be cooled completely before topping with caramel mixture.

Fill a small bowl with hot water and place your pastry brush in the water. In a separate small bowl stir malted milk powder into heavy cream and set aside.

While the short bread is cooling, make your caramel. Heat sugar and water in a large sauce pan over medium-low heat. Stir frequently until sugar dissolves. Increase heat to medium and bring to a boil. Do not stir, allowing sugar to brown. Every 5 minutes or so, swipe your wet pastry brush against the sides of the pan to prevent burning.

Once the caramel is a deep Amber color, after about 15 minutes, add honey and bring to a boil again. Using a wooden spoon, stir frequently and cook another minute.

Add in butter, stirring constantly to mix. Add cream-malt mixture and salt, and whisk until all ingredients are incorporated and caramel is smooth. Remove from heat.

Fold in walnuts, then pour entire mixture over cooked crust. Sprinkle a generous amount of fresh cracked sea salt over top. Transfer pan to refrigerator and allow bars to cool for at least 30 minutes.

Once cooled, lift contents out of the pan using the parchment overhang, and transfer to a cutting board. Cut into bars, approximately 8 rows vertically and 3 rows horizontally. Serve bars at room temperature.Stored in an airtight container in the refrigerator, bars will keep one week.