Line a rimmed baking sheet with parchment paper. Set aside.
Combine the flour, 6 tablespoons butter, sugar, baking powder and salt in a food processor. Process until butter is incorporated, 15 seconds. Add cheddar and remaining 6 tablespoons cut up butter, pulse until cheese and butter are pea sized, 12 pulses. Transfer to a large bowl. Stir in jalapeños until coated with flour.
In a small bowl beat milk and eggs together. Make a well in the center of the flour mixture. Pour milk mixture into the well and gently combine mixture with a rubber spatula. Fold mixture from the edge of the bowl inward until a shaggy dough forms. Do not overmix.
Turn dough on to a well floured surface and knead by hand until dough comes together, about 3 turns. Use floured hands and a bench scraper to shape the dough into a 15"X3" rectangle. Use extra flour if it gets too sticky.
Using the bench scraper or a knife cut the rectangle into 6 rectangles. Cut each rectangle into 2 triangles. Do this by cutting each rectangle diagonally. This will give you 12 scones. Transfer scones onto the baking sheet, spacing them 1" apart. Cover sheet with plastic wrap and put in the fridge for 30 minutes to 24 hours.
Heat the oven to 425'. When ready to bake the scones remove the plastic wrap and bake the scones for 18 minutes, rotating them halfway through. Melt the 3 tablespoons of butter while scones are baking. Remove scones from oven and brush with melted butter. Return scones to oven and continue baking until golden brown on top, about 5 minutes.
Transfer scones to a wire rack and let cool for 10 minutes before serving.
