In a large bowl or the bowl of a stand mixer with paddle attachment, beat the butter and both sugars together until light and fluffy (2-3 minutes) scraping down the sides of the bowl as necessary.
3/4 Cup Unsalted Butter, 1/2 Cup Granulated Sugar, 3/4 Cup Light Brown Sugar
Add the eggs one at a time, beating well between each and scraping down the sides regularly.
3 Eggs
Combine the buttermilk and apple sauce in a jug.
1/2 Cup Buttermilk, 1/2 Cup Apple Sauce
Add a third of the dry ingredients and mix until just combined. Now add half the buttermilk and apple sauce and mix it through. Repeat until everything is added, mixing only until everything is just incorporated.
Finally add the apples and pecans and mix through.
2 Granny Smith Apples, 3/4 Cup Pecans
Tip the batter into the prepared tin and spread it out evenly.
Bake for 45-50 minutes until a toothpick comes out with just a few wet crumbs attached.
Let it cool in the tin for 10 minutes before turning out onto a platter or cake stand.
FOR THE CARAMEL ICING:
Add the butter, sugar and cream to a small saucepan, stirring over medium heat. Once the butter has melted and the sugar dissolved, bring to the boil, then reduce the heat and simmer for 1 minute.
1/4 Cup Unsalted Butter, 1/2 Cup Dark Brown Sugar, 1/4 Cup Heavy Cream
Remove the pan from the heat and let it cool for a few minutes before whisking in the powdered sugar.
2/3 Cup Powdered Sugar
Drizzle over the cake immediately then let it set for a few minutes before scattering over the remaining pecans.
Small Handful Pecans
Notes
To measure flour correctly: fluff up the flour in the container, then spoon it into the cup measure. Level it off with the back of a knife.
Bundt cake will keep for 5 days in the refrigerator.