In a large bowl, beat the butter until smooth, and then add the sugar, beating until the mixture is light and fluffy in texture.
Add the eggs, Meyer lemon juice and zest, beating until thoroughly incorporated.
In a separate bowl, add the dry ingredients, mixing the flour, oats, chopped nuts, cinnamon, baking powder and salt until well blended.
Gradually spoon the dry ingredients into the egg mixture, beating until incorporated.
Cover the dough and refrigerate for an hour or two, until the dough is firm enough to work with.
Preheat oven to 375°, and line a baking sheet with parchment paper.
Shape tablespoonfuls of the dough into balls, and place on the prepared baking sheet about 2-inches apart. Flatten the balls into rounds with the back of a spoon (dip it into water to if it begins to stick).
Bake in the oven for only 5 to 8 minutes. The cookies should be fragrant and golden brown around the edges.
Cool for 20 to 30 minutes on a rack before eating.