Heat oven to 350.
Grease the bottom and sides of 2 loaf pans.
In a medium bowl, combine the flour, spices, salt, and baking powder.
In a large bowl, combine the sugar, ginger, zest, juice, vanilla, and grated parsnips and let sit for 5-10 minutes, until parsnips moisten or "sweat."
Whisk in oil and melted butter to combine.
Add eggs one at a time and whisk to combine.
Stir in one-third of the flour mixture until roughly combined.
Stir in 1/4 c milk until roughly combined.
Stir in the second third of the flour mixture until roughly combined.
Stir in the remaining 1/4 c milk until roughly combined.
Stir in the final third of the flour mixture until just combined.
[If dough looks altogether too dry, add an additional 1/4 c milk]
Fold in the nuts.
Divide the batter evenly between the two pans.
[This recipe makes about 6 cups of batter, in case you decide to divide differently]
Bake for 45-55 minutes, until a butter knife comes out clean towards the centre.
Cool breads in their pans on a wire rack for 10 minutes.
Remove breads from their pans and cool completely on a wire rack.
To make the glaze: combine icing sugar and cardamom.
Add the vanilla and [optional] food colouring, and then the lemon juice by the teaspoonful, stirring vigorously until smooth and thick.
Drizzle the glaze over cool loaves.