Preheat the oven to 400°F. Place 1 tablespoon of the butter in an 8×8-inch baking pan and place it in the oven for about 3-5 minutes while the oven preheats. Once the butter is melted, brush it across the bottom and up the sides of the pan. Set aside.: As the oven warms, the butter melts quickly and begins to shimmer, and you can hear a faint sizzle when it reaches temperature. That buttery scent is the first cue that everything is coming together. Brushing the melted butter across the bottom and up the sides creates a nonstick barrier and encourages the outer edges of the biscuits to brown evenly. A common mistake is leaving the butter in the oven too long so it browns or burns, which would impart a bitter flavor, so watch carefully during those 3 to 5 minutes.
Cut the remaining butter into small pieces. Keep cold until you are ready to use it.: The small cold nuggets of butter should feel firm and cool to the touch, and when you press them they should not slump. Cold butter creates steam pockets during baking that lift and separate layers, so do this step quickly to prevent warming. If the butter softens during prep, pop it back into the refrigerator for a few minutes instead of continuing, because warm butter will yield greasy, dense biscuits.
In a large bowl, whisk together the flour, sugar, baking powder, baking soda, and salt. Add the cold butter pieces; toss in the flour mixture, then use your fingertips to smash the butter into flat, irregular pieces.: The dry mix should look homogenous and pale before the butter goes in, and after you smash the butter it should resemble coarse crumbs with some larger flakes visible. That visual texture is crucial, because visible pockets of butter mean steam will form and create flakiness. When you press the mixture it should feel cool and slightly grainy. Avoid overworking with too much heat from your hands, which will make the butter merge fully into the flour and reduce flakiness.
Add the blueberries and toss to combine. Gently stir in the buttermilk until no dry pockets of flour remain.: As you fold in the fresh blueberries , they will contrast the dry mix with cool, juicy weight. Gently incorporate the buttermilk so the dough comes together without smashing or tearing the berries. The mixture should be moist and slightly sticky, not wet and runny. If you see streaks of dry flour, keep folding just until they disappear, because overmixing activates gluten and toughens the final crumb. A frequent error is pressing or stirring vigorously, which bruises the berries and bleeds color into the dough.
Transfer the dough to the prepared baking pan. Use a spatula to spread the dough evenly across the pan, including into the corners.: When you scrape the dough into the 8×8-inch pan , it should glide with some resistance, and the surface will look matte and slightly bumpy from the berry pockets. Press gently to distribute so the corners are filled, because uneven thickness will lead to inconsistent baking times across the pan. You want an even layer for uniform browning. Do not press so hard that you compact the dough, because that would reduce rise during baking.
Lightly spray a bench scraper with nonstick cooking spray and use it to score the dough into 9 equal squares, but do not separate.: The scored lines should be clean and visible, and this scoring helps you portion the biscuits after baking while allowing them to bake as one unit, keeping moisture in. The surface gives a hint at structure, with visible flake edges where the butter is concentrated. Resist pulling the pieces apart before baking since separation can create drier edges that bake too quickly and brown too much.
Bake for 40-45 minutes or until the tops of the biscuits are browned and a paring knife inserted into the center biscuit comes out clean. Let the biscuits cool for 5 minutes.: In the oven you will see the tops develop a deep golden brown and sense a warm, rich aroma of butter and sweet blueberries . The sound is quiet, but the visual cue of even browning and a clean knife test means they are done. Cooling for 5 minutes lets the interior finish setting, so the biscuits hold together when turned out. One mistake is removing them too early which leaves a gummy center, so rely on both color and the knife test.
Prepare the honey butter: In a small microwave-safe bowl, combine the butter, honey, and salt. Microwave until the butter is melted, 30-60 seconds, and stir to combine.: In a small microwave safe bowl, combine the butter, honey, and salt. Microwave until the butter is melted, 30 to 60 seconds, and stir to combine : When the butter melts, it releases a warm, toasted scent that blends with the floral honey. Stirring creates a glossy mixture that will glaze the biscuits. Be careful not to overheat in the microwave which can make the honey separate; short bursts and stirring prevent that. If your microwave runs hot, reduce the time and stir more frequently to combine evenly.
After the biscuits have cooled for 5 minutes, turn them out onto a baking sheet, then flip them back onto a wire rack (they should be top-side up again). Brush the tops with all of the honey butter. Cool for an additional 10 minutes before using a serrated knife to cut the biscuits along the scored marks. Serve warm.: The act of turning them out reveals the browned bottoms and ensures the tops remain facing up after flipping. Brushing the warm tops lets the honey butter soak in slightly, creating a glossy sheen and added flavor. The honey will sit in small crevices, and the aroma becomes irresistible. Avoid applying the glaze while the biscuits are piping hot out of the oven, since extremely high heat can cause the butter to run off.
Cool for an additional 10 minutes before using a serrated knife to cut the biscuits along the scored marks. Serve warm: As they cool, the biscuits set fully and the juices from the blueberries redistribute, so cutting yields clean squares without tearing. The crumb should be tender and moist with visible fruit pockets. Serve when still warm for the best contrast of textures. A common slip is slicing too soon, which can crush the structure and make crumbly edges.