Preheat oven to 325° F convection or 350° F static.
Lightly oil and flour with gfJules Flour a bundt pan or large loaf pan.
Cream butter and sugar, whipping at medium-high speed for at least 5 minutes, until lighter and fluffy. Add vanilla extract, sour cream and eggs, one at a time, beating between additions.
In a separate bowl, combine dry ingredients and whisk to mix.
Slowly stir dry ingredients into larger mixing bowl, alternating with coffee and milk (or OWYN). Stir to fully integrate but do not over-mix.
Melt butter for swirl, then add brown sugar and cinnamon. Set aside.
Spoon approximately half of the cake batter into the prepared pan. Spread the swirl ingredients on top, cutting through with a knife, if desired, then spoon remaining cake batter on top of swirl. Smooth top to level.
Bake in preheated oven for approximately 55 minutes. The cake is done when a toothpick inserted into the center comes out with only a few dry crumbs on it.
Remove to cool on a wire rack for 5 minutes, then loosen the sides if necessary and flip onto a plate.
Once fully cooled, drizzle mixed glaze on top or sprinkle with powdered sugar.