Stir flour, sugar, salt, black pepper and sesame seeds together. Add in the cold butter and cut it in with a pastry blender or a fork (more tedious) or your fingers until you get coarse crumbs. Stir in milk to form into a rough dough and scrape it out onto a clingfilm / plastic wrap.
Using your hands, gently squeeze to gather the dough together. If it is too crumbly, add in more milk, teaspoon by teaspoon until you get a soft dough. Press the dough into a disk, wrap it with plastic wrap and rest at room temperature for 1 hour.
(If you are living in a very warm place like Singapore, refrigerate the dough for 45 minutes. Take it out and leave it on the table counter for 15 minutes to let it soften before working on it.)
Preheat the oven to 175 degrees Celsius. Line a baking sheet with baking parchment.
Unwrap the disk and roll it out as thinly as possible with a rolling pin. Trim the edges and cut into desired shapes. Transfer the dough onto the baking sheet and bake for 12 to 15 minutes until lightly golden and crispy. Let the crackers cool completely before storing in an airtight container.