Prepare baking sheet with parchment paper or baking mat.
In a medium bowl, combine flour, sea salt, baking powder, brown sugar, and cinnamon.
Stir to combine.
Use a fork or pastry blender to cut in butter. The mixture will resemble crumbly lumps. (see my hack for cutting in butter)
Add vanilla and milk and stir gently just until combined.
Move dough from bowl to baking sheet and form a rounded loaf.
Divide the loaf into 8 wedges with a floured knife. Do not cut all the way through the bottom.
Bake for 20 to 25 minutes at 375 until golden brown.
While that’s baking, prepare the butter by combining all butter ingredients in a small bowl. I use a hand mixer to whip it into a lighter, airier whipped butter.