In a medium bowl, whisk together flour, salt, baking powder, and baking soda. Set dry ingredients aside.
In the bowl of an electric mixer, combine butter with both sugars; beat until light and fluffy. Add vanilla, milk, and eggs; mix well. Add reserved dry ingredients, and beat until just combined. Remove bowl from mixer, and fold in oats, chocolate, and pecans. Place dough in the refrigerator until firm, at least 2 hours or overnight.
Heat oven to 350 degrees. Line two baking sheets with parchment paper, and set aside. Remove dough from refrigerator. Using an ice-cream scoop, shape into 2-inch-diameter balls. Place six balls on each baking sheet, spaced 4 inches apart, and press down
Transfer to oven. Bake until golden, but still soft in center, 15 to 16 minutes. Remove from oven, and place on a wire rack to cool completely. Repeat with remaining dough. Store in an airtight container up to 2 days.
You can substitute raisins for the chocolate chunks.