I found this recipe for Irish Brown Bread on Brown Eyed Baker, and she adapted her version from David Lebovitz. This is a fairly simple bread to make, and it has a distinctly different flavor than traditional yeast breads.
Irish Brown Bread
1 cup plus 1 1/2 tsp. wheat flour
1/2 cup plus 1 1/2 tsp. wheat bran
2 cups flour
3/4 tsp. baking soda
1/2 tsp. salt
2 Tbsp. unsalted butter, cold and cut into small pieces
1 1/4 cups buttermilk
1 tsp. molasses
Preheat oven to 350°F. Line a baking sheet with parchment paper or a silicone baking mat. Whisk together the wheat flour and wheat bran in a large bowl.
In a medium bowl, whisk together the white flour, baking soda and salt. Add to the wheat flour mixture, and whisk to combine. Add the butter pieces, and rub them into small pieces with the flour mixture using your fingers, until as small as possible. Stir in the buttermilk and molasses until the dough is uniformly damp. Turn out onto a lightly floured countertop and knead gently, until the dough forms a smooth ball.
Use a sharp serrated knife to slice a cross deeply into the top of the bread, about 1-inch deep. Place the loaf on the hot baking sheet. Bake for about 30 to 35 minutes, or until the loaf is firm on top and when you tap the bottom, feels hollow. Remove from the oven and cool on a wire rack for about one hour before serving.