Vegan Chocolate Orange Cookies (Cookie Bars)

• 1 Tablespoon flax seeds ground
• 200 g vegan margarine (¾ cup)
• 150 g caster sugar (¾ cup)
• 100 g brown sugar ½ cup, soft
• 1 Teaspoon vanilla extract (optional)
• 290 g self-raising flour (2 cups + 2 tablespoons)
• 40 g cocoa powder (5 tablespoons)
• 80 g dairy-free chocolate chips (½ cup)
• 3 Tablespoons orange zest

Optional topping:

• dairy-free chocolate just enough to drizzle on top, melted
• orange zest extra