Heat oven to 375 degrees F. Cream butter and granulated sugar in large bowl of electric mixer. Beat in eggs, one at a time, beating well after each addition. Stir in 1 Tablespoon coffee and the vanilla.
Mix flour, baking powder, baking soda, and salt. Add to flour mixture, alternating with the sour cream, to the butter mixture, beating well after each addition. Reserve.
Soak currants in hot water to cover, for 8 to 10 minutes. Drain and discard water. Combine currants, brown sugar, walnuts, cinnamon, and coffee powder in a small bowl.
Spread a fourth of the reserved batter into bottom of a well-buttered 12-cup Bundt pan or 10-inch tube pan. Sprinkle with a third of the currant mixture. Repeat layering twice, ending with batter. Bake until a wooden pick inserted in the center is withdrawn clean, about 45 to 50 minutes. Cool on a wire rack for 20 minutes, then turn out cake to cool completely.
When cool, stir together glaze ingredients until smooth enough to drizzle and spoon over cake. (if glaze is too thick, add a little more half-and-half, drop by drop)
Recipe by The Culinary Cellar at https://theculinarycellar.com/cuisine-magazine-march-1979/