• Pre-heat the oven to 325 degrees Fahrenheit. Line an 8" x 4" loaf pan with parchment paper, leaving an overhang on all sides.

Make the cinnamon crumb swirl:

• Melt the butter in a medium saucepan over medium heat. Add the panko and stir till golden brown. Add the brown sugar, cinnamon and salt and stir till well combined, breaking up any large chunks. Transfer to a bowl and let cool (you can place in the fridge if you like).

Make the cake:

• Beat the butter and cream cheese till light and fluffy. Add the sugar and beat again. Add the eggs, vanilla and sour cream and beat till combined. Add the flour, baking powder and salt and beat till combined (do not over beat).
• Add 1/3 of the batter to your prepared loaf pan. Use a small angled spatula to spread evenly. Top with half the cinnamon crumb mixture, spreading evenly. Top with 1/3 of the batter and spread again. Top with the remaining cinnamon crumb mixture. Finish with the remaining batter. Run a thin knife through the batter once lengthwise and once crosswise.
• Bake the cake till golden brown and a tester tests clean - 55 - 65 minutes (you can start testing after 50 minutes). Let the cake cool in the pan on a wire rack for 20 minutes, then use your parchment "sling" to transfer the cake to the wire rack to cool completely.

Make the frosting:

• Beat the cream cheese and butter till light and fluffy. Add the confectioner's sugar, vanilla, salt and 1 tablespoon of the milk or cream. Beat till well combined. if the frosting is too stiff you can add more liquid, a bit at a time, till the desired consistency is achieved.
• Spread the frosting on the cooled cake.