Beat peanut butter and shortening together in a large bowl with an electric mixer on medium speed for 30 seconds. Add chipotle powder, baking soda, and salt, beating until blended. Beat in eggs, vanilla, and freshly grated lime peel. Beat in oats and flour. Stir in peanut butter chips, if desired.
Drop by rounded teaspoonfuls onto parchment paper-lined cookie sheets.
Bake for 8 minutes. Cool slightly, and transfer to wire racks to cool completely.