Place rack in middle of oven and preheat oven to 350 F.
Grease and dust flour in 8.5 x 4.5 inch loaf pan.
Sift the AP flour, baking soda, baking powder and salt and mix. Set aside.
In stand mixer on medium, beat butter until light fluﬀy about 4 minutes, then add sugar and beat another 3 minutes.
Add the eggs, one at a time, scraping sides every so often.
On slow speed, add the vanilla, grapefruit juice/zest and cream.
Mix in the flour dry mix until combined.
Pour into loaf pan and spread evenly with spatula.
Bake for 50-60 minutes until tester comes out clean.
Cool in pan for about 10 minutes.
Drizzle with grapefruit syrup in pan and allow cake to soak for about 3 minutes.
Transfer to cooling rack.
Once cake has completely cooled, drizzle with icing.
Sprinkle toasted chopped hazelnuts and garnish with grapefruit zest.