Beat butter, brown sugar, and granulated sugar until creamy

Add milk and vanilla, mixing until combined

Gradually mix in heat-treated flour until soft dough forms

Fold in mini chocolate chips

In a saucepan over low heat, melt white chocolate chips, sweetened condensed milk, and butter, stirring until smooth

Remove from heat and stir in vanilla and salt

Line an 8×8-inch pan with parchment

Spread half of fudge mixture into the pan

Drop spoonfuls of cookie dough over fudge and gently press slightly

Pour remaining fudge on top and smooth evenly

Sprinkle extra chocolate chips if desired

Refrigerate at least 3–4 hours or overnight to set