• Prepare lemon curd.
• Preheat oven to 350°F.
• Combine the flours, salt, baking soda, and cream of tartar in a small bowl and set aside.
• In a large bowl, cream butter and sugars until light and fluffy. Beat in the oil, egg, and extracts. Add the flour mixture to the creamed mixture and stir until combined.
• Drop one tablespoon of dough (I used a #50 scoop) into each cup of a greased mini muffin tin or lined with mini cupcake liners. Bake for 8 minutes.
• Remove from the oven and, using the end of a wooden spoon handle, make an indentation in the center of each cookie. Fill with a teaspoon of lemon curd.
• Return to the oven and bake for an additional 4 minutes, or until cookies are firm and lightly browned on the sides. Remove to wire racks to cool.
• Sprinkle the edges of the cookies with powdered sugar.

Lemon Curd

• In a large mixing bowl, beat the butter and sugar with an electric mixer, until well combined. Add the eggs and yolks and beat for 1 min. Add the lemon juice and mix until blended – the mixture will look lumpy.
• In a medium, heavy-based saucepan, cook the mixture over low heat until it melts. Increase the heat to medium and cook, stirring constantly, until the mixture thickens. It should leave a path on the back of a spoon and will read 170°F on a thermometer. Don’t let the mixture boil. (Once it was completely melted, mine thickened and reached 170º in just a few minutes, so watch it closely.)
• Remove the curd from the heat; stir in the lemon zest. Transfer the curd to a bowl. Press plastic wrap on the surface of the lemon curd to keep a skin from forming and chill the curd in the refrigerator. The curd will thicken further as it cools. Covered tightly, it will keep in the refrigerator for a week and in the freezer for 2 months.