Place 1/3 cup flour and the milk into a small pot and whisk together until fully combined.
Set the heat to medium and whisk continuously until it thickens into a paste. Remove from the heat and set aside.
Pour the warm water into the bowl of a stand mixer. Sprinkle the yeast on top, add a pinch of sugar and allow it to develop for about 5-10 minutes, until frothy.
Add the flour, granulated sugar, eggs, vegetable oil, salt and the flour paste from Step 2. Attach the dough hook attachment and knead on medium speed for about 7 minutes until the dough forms a smooth, sticky ball.
Grease a large bowl with oil and place the dough in the bowl. Rotate the dough once so that all sides are covered in oil. Cover the bowl with plastic wrap, place it in a warm area and allow it to rise until doubled in size. This can take 2-4 hours, depending on how warm your kitchen is.
To make the butter block, place the butter between two large sheets of parchment paper. Use a rolling in to roll it into a 9x12” rectangle. Place it on a baking sheet and chill it in the fridge until ready to use. You can do this right after you make the dough, or about 30 minutes before the dough is finished rising.
Once the dough has doubled in size, punch it a couple times to deflate, then turn it out onto a floured surface. Use a rolling pin to roll it into a 13x18” rectangle.
Gently peel one sheet of parchment paper off of the butter block. Invert the butter block onto one half of the dough rectangle. Leave a 1 inch border of dough around the 3 sides of the butter. Gently peel the second sheet of parchment paper off the butter. You can use a spatula if you’re struggling with keeping the butter in an even layer.
Fold the dough in half like a book, so that the butter is sandwiched between two layers of dough. Pinch the edges of the dough so that the butter is sealed in the middle. Then fold the dough in 3 like a letter, by folding the bottom third upwards, then the top third downwards.
Fold the dough in half horizontally like a book. Wrap it in plastic wrap and chill in the fridge for 30 minutes. This will keep the butter cold and prevent it from squishing out of the dough.
Roll the dough out again to a 13x18” rectangle. Fold it in thirds like a letter horizontally, by folding the left third into the middle, then the right third on top, which will create a long rectangle of dough.
Fold the dough in half vertically, bringing the bottom half up to meet the top. Wrap in plastic wrap again and chill for 45 minutes.