Coffee and Walnut Loaf Cake

Coffee and Walnut Loaf Cake

2 tablespoon Instant coffee
1 tbsp Boiling water
60 g Walnut halves (½ Cup)
225 g Unsalted butter at room temperature (1 Cup)
220 g Soft brown sugar (1 Cup packed)
250 g Self raising flour (1 Cup and 7 tablespoons) or use plain/all-purpose flour and 1.5 teaspoons of baking powder)
¼ teaspoon Fine salt
1 teaspoon Ground cinnamon
4 Large eggs at room temperature (US extra large)
1 tablespoon Vanilla extract