Prep: Preheat the oven to 350°F. Line a baking sheet with parchment paper. Prepare a cooling rack on the counter with paper towel or parchment paper under it.
Baste & cook bacon: Lay the bacon flat on the baking sheet in a single layer. Brush the 3 tablespoon of maple syrup over the bacon. Then bake for 25-30 minutes, turning half way through. Remove the bacon when it is nice and crispy (it won't be 'candied' yet).
Cool bacon, turning to prevent sticking: Immediately transfer the bacon to the cooling rack. Cool for about 10 minutes, flip it (to avoid it sticking to the rack), and cool for another 10 minutes. The sugar from the maple syrup will become candied as it cools.
MAKE AHEAD: After the bacon cools on the rack, you can store it in the fridge for several days in an airtight container or plastic bag.
Make the scone dough
Mix dry ingredients: In the bowl of a stand mixer, add in the following: 3 cups of flour, 1½ teaspoon baking powder, ¼ teaspoon baking soda, ½ teaspoon kosher salt. Mix briefly (5 seconds) to distribute the dry ingredients.No mixer: a stand mixer isn't required. Use a large bowl if doing this by hand.
Add butter: add the 1 cup of cold, cubed or grated butter (see note) to the mixing bowl. Beat for 20 seconds on low (higher speeds will make the flour fly out of the bowl in a cloud).No mixer: use grated butter and mix into flour mixture by hand.
Add-ins: Crumble 8 slices the bacon and add to the bowl. Also add in the ½ cup of walnuts (or pecans), and the 2 teaspoon of lemon zest. Briefly mix until just incorporated (do not overmix).No mixer: mix with a spoon or spatula until just incorporated.
Whisk wet ingredients in a separate bowl: whisk together the cold ½ cup heavy cream, 1 cold egg, and ½ cup cold maple syrup. Cold ingredients ensure you won't break down (melt) the butter in the dough. Whisk until completely incorporated. (There is no worry about overmixing for this step).
Pour wet mixture into dry: Pour the wet mixture into the bowl with the dry ingredients and mix on medium speed until the dough just comes together (30-60 seconds). Do not overwork the dough here.No mixer: mix with a spatula by hand until it comes together.
Transfer to floured surface & shape: Transfer the dough to a lightly floured surface. Gently shape it into a circle that's about 1 inch thick (or a long rectangle, also one inch thick). Do not kneed it or continuously reshape it (which will overwork it and make the scones tough). Cut into 8 wedges.
Chill for 15 minutes: for foolproof scones, chill the dough for 30 minutes. The cold dough keeps it from spreading when baked. Note: the original recipe from the cookbook doesn't require this step, but I personally do it every time to make sure I don't accidentally end up with flat scones).MAKE AHEAD: The scones at this point can be stored in the fridge (covered) for several days, or the freezer for a month. Bake when ready to eat (straight from the fridge or freezer, adding a few minutes to cooking time for frozen dough).
Bake at 350°F for 25-30 minutes on a parchment-lined baking tray. They are done when they turn golden brown. If using an instant-read thermometer, they are done when they reach 170°F. Let cool for 5 minutes (on the baking pan is fine). Make the glaze while they cool.
Make the glaze & top with bacon
Make the glaze: Mix the 1 cup of powdered sugar, 3 tablespoon syrup, 3 tablespoon melted butter, and ½ teaspoon vanilla in the stand mixer with the paddle attachement (or by hand). Mix until smooth.
Spread about 2 tablespoon of the glaze onto each scone. Top each scone with half a piece of bacon (crumbled).
Store leftovers
Leftovers can be stored on the counter in an airtight container for a day or several days in the fridge. Reheat in the oven at 350°F on a baking tray loosely tented in foil for about 10 minutes.
Notes
Butter note: You can freeze butter ahead of time and then grate it on a cheese grater. This is the easiest way to incorporate it into the dough, especially if you are mixing it by hand (no mixer option).Adapted from Eat Delicious - see this section about changes I've made from the original.