In a heavy bottom saucepan, melt butter over low heat and bring to a boil. Simmer over low flame for approximately 5 minutes, being careful not to burn the butter.
Gradually add flour, while stirring over medium heat for 5 additional minutes.
Continue to roast and stir the mixture over low heat until the it turns dark tan and has a nutty aroma. This should take approximately 20 minutes.
Mix date molasses and water in a separate small saucepan and bring to a boil. Carefully pour the molasses into the roux (flour and butter mixture). Mix thoroughly until completely combined. There should be no streaks of light and dark colors. The halwa mixture should be a solid brown color.
Transfer the halwa mixture into a loaf pan or other small dish. Press down firmly to pack the halwa using a spatula or the back of a wooden spoon. Slice into 1"-2" portions using a knife. Cool completely before serving.
Notes
If you love cardamom like I do, here's where you can add 1-2 teaspoons of cardamom powder, or to taste. This was not in my mom's halwa recipe but I just look for any opportunity to include cardamom in my recipes.
Here is another optional tip to take your halwa recipe to the next level. Garnish each cube with a toasted walnut halves, cashews, or a toasted almonds.
I halved the original halwa recipe found in my cookbook to make a smaller batch, you can easily double the recipe.
The halwa should be approximately 1" thick. Use a pan that will allow you to achieve this thickness. If the pan is too large the halwa will not be thick enough.
If this halwa recipe doesn't come out as thick as you'd like, just reheat it briefly in the same saucepan then pour into a smaller pan or dish.
Halwa is usually even darker in color. I used homemade Date Molasses that was not as dark as store-bought molasses. If you want the color to be darker, use this Date Molasses.
Store halwa in an airtight container either at room temperature or in the refrigerator.