Chop or crush 2 c. of spruce tips and place them in a heat proof bowl. Pour the boiling water over the crushed tips and cover, and allow them to infuse for 15-30 minutes, until cooled a bit.
Using a coffee strainer, strain the crushed tips from the infusion. In a blender, add the additional 1 c. of spruce tips and the infusion. Blend for 15 seconds. Strain the infusion again to remove the solids. You will need 2 c. of infusion to continue, it will be milky-white.
In a sauce pot, combine the cornstarch, sugar, and pinch of salt and whisk until no lumps can be seen. Add 2 c. of spruce infusion, egg yolks, and the Orange Juice.
Over medium-low heat cook the curd slowly while running a rubber spatula around the sides and bottom of the sauce pot often. It will take 5-8 minutes for the curd to thicken, and once it starts boiling slowly, cook for an additional minute. Stir in the butter and remove from the heat.
Allow the curd to cool in a bowl, covered with plastic wrap placed directly on the surface (otherwise a skin will form) for about 15 minutes. Stir in the minced spruce tips, then recover and refrigerate until service