Preheat the oven to 350°F (175°C). Grease your baking pan with butter or non-stick spray and set aside.
Combine 1 3/4 cups of flour, 1/2 cup of sugar, and 1/2 teaspoon of cinnamon in a mixing bowl. Cut in the cold butter using a pastry cutter or fork until the mixture resembles coarse crumbs. Set aside for the crumble topping.
2 large eggs, 1 teaspoon ground cinnamon
In a separate large bowl, whisk together eggs, milk, vegetable oil, vanilla extract, remaining sugar (1/4 cup), and the remaining 1/4 cup of flour until smooth and well combined.
1 teaspoon vanilla extract, 1 cup milk, 2 large eggs, 1/2 cup vegetable oil
Pour the batter into the prepared baking dish, spreading it evenly with a spatula. Sprinkle the cinnamon crumble evenly over the batter.
1 teaspoon vanilla extract
Bake in the preheated oven for 35 minutes, or until the top is golden brown and a toothpick inserted into the center comes out clean. The cake should be puffed and set, with a slightly cracked top.
Allow the coffee cake to cool in the pan for 10 minutes before transferring to a wire rack. Serve warm or at room temperature, revealing a moist interior topped with crunchy crumble.