Turn the oven down to 350F.
In a large saucepan over medium high heat, add the sugar, water and dark golden corn syrup. Bring to a boil, then turn down the heat until it reaches a low simmer. Allow to simmer for about 10 minutes, stirring frequently, until the mixture is amber colored.
2 cups granulated sugar, ½ cup water, ½ cup dark golden corn syrup
Add the lemon juice and zest, mixture may bubble up, stir until smooth. If the syrup gets hard and does not dissolve into the lemon juice gently heat until smooth.
½ cup lemon juice, 1 tablespoon lemon zest
Add the butter and whisk until smooth.
¼ cup butter
Allow the mixture to cool slightly before adding the eggs, one at a time, whisking well after each addition. Strain into a large bowl to remove any lumps.
3 large eggs
Mix in the breadcrumbs, then transfer the whole filling mixture to the prepared tart crust.
1 ½ cups breadcrumbs
Place the tart pan on a baking sheet to catch any spills, then bake in the oven for 35-40 minutes, or until the filling is set but still wobbly.
Remove from oven and allow to cool for at least 1 hour before sprinkling with powdered sugar
Powdered sugar for dusting